Method and apparatus for PLMN / SNPN verification

Abstract

Embodiments include methods for a Network Repository Function (NRF) of a first communication network. Such methods include receiving, from a Network Function service consumer (NFc) of a second communication network having a plurality of equivalent network identifiers, an access token request, the access token request comprising the plurality of equivalent network identifiers, wherein the access token request is a request for an access token for a service provided by a Network Function service producer (NFp) of the first communication network. Such methods include generating the access token comprising a claim with the plurality of equivalent network identifiers of the second communication network. Such methods include sending the access token towards the NFc.

Description

METHOD AND APPARATUS FOR PLMN / SNPN VERIFICATIONINTRODUCTIONThe present disclosure generally relates to the field of wireless communication networks and, more particularly, to the verification of Public Land Mobile Network (PLMN) and or Standalone Non-Public Network (SNPN) in service request authorization in interconnect scenarios.3rd Generation Partnership Project (3GPP) Fifth Generation (5G) systems uses a service-based architecture (SBA) that leverages service-based interactions between Core Network (CN) Network Functions (NFs). NFs in this regard enable other authorized NFs to access their services. Alternatively, or in addition to predefined interfaces being defined between network elements of a 5G system, an instance of an NF needing to consume a service of a certain type queries a so-called Network Repository Function (NRF) to discover and communicate with an instance of another NF that provides that certain type of service.In particular, NFs can take on a provider role as a provider of a service, i.e., Network Function Service Provider (NFp) and / or a consumer role as a consumer of a service, i.e., Network Function Service Consumer (NFc). In an end-to-end (e2e) an NFc requesting a service from an NFp, includes an end user initiating, via his User Equipment (UE), a request that requires network services. For example, this could be accessing a web page, starting a video call, or sending a message. The request from the UE is received by the Radio Access Network (RAN) and then forwarded to the 5G CN. In the 5G CN, the request is handled by various NFs as specified in more detail in this specification. A specific NF that is acting as a NFc identifies the need for a service provided by another NF, the NFp. For example, if the UE is trying to establish a session, the Session Management Function (SMF) may need to interact with the Policy Control Function (PCF) to determine the policies for that session. The NFc sends a service request to the NFp. This interaction is part of the above-mentioned SBA in the 5G core, where NFs communicate with each other using standardized Application Programming Interfaces (APIs) and protocols. This communication could involve various types of services, such as authentication, authorization, session management, and policy enforcement. The NFp processes the request and provides the necessary service back to the NFc. For example, the PCF may provide the necessary policy rules back to the SMF, which then uses these rules tomanage the session for the UE. The NFc, now equipped with the necessary information or service from the NFp, can proceed with fulfilling the original request from the UE. This could involve setting up a session, providing access to network resources, or enforcing specific policies. Finally, the user perceives the service they requested. This could be a successful web page load, a video call connection, or any other network service that was initiated.3GPP describes security architecture and procedures for 5G systems in 3GPP Technical Specification (TS) 33.501, Security architecture and procedures for 5G system (V17.14.0). As defined in 3GPP TS 33.501 (V17.14.0), a service request process, where an NFc requests a specific service from an NFp comprises: 1) an NFc requesting and obtaining an access token for the specific service from the NRF acting as an authorization server for the NFc, (2) the NFc including the access token in a new request for the specific service, and (3) a receiver of the new request authorizing the request and granting access to the service based on the access token. Such authorization of a service request process may be performed in an inter-PLMN interconnect scenario as defined in clause 13.4.1.2 of 3GPP TS 33.501 (V17.14.0), where the NFc is located in a first PLMN (cPLMN) and the NFp is located in a second PLMN, (pPLMN).In this specification, when referring to communication networks it is to be understood that the networks facilitating communication between two entities, such as two NFs may either be the same network or different networks. This distinction is important for understanding how data and signals are transmitted and managed during communication. When two entities communicate over the same network, they are both connected to the same PLMN or the same SNPN having a common network identifier, operated by the same operator and sharing the same network infrastructure. On the other hand, communication between two entities can also occur over different networks such as in the above mentioned inter-connect scenario. In this scenario, each entity is connected to a different PLMN or SNPN, which don’t share any common network identifiers, and are operated by separate mobile network operators. These networks have distinct infrastructures and unique PLMN identifiers. To facilitate communication between different networks, inter-network protocols and agreements, such as roaming and interconnection agreements, are essential. Throughout this specification, PLMN use cases and scenarios also apply for SNPN unless explained otherwise.An example of inter-PLMN interconnect scenario is service access authorization in the roaming scenario where the NFc is located in the visited PLMN and the NFp is located in the home PLMN. The inter-PLMN interconnect scenario applies also to the case where the NFc is instead located in a first SNPN and the NFp is located in a second SNPN.In the inter-PLMN interconnect scenario, communication networks of NFc and NFp interoperate with each other to provide continuity of service. Communication between different networks can increase the risk of potential security breaches due to e.g., impersonation attacks. To prevent impersonation attacks and to maintain integrity and confidentiality of communication, 3GPP TS 33.501 (V17.4.0) specifies that the destination network receiving a message from a source network must be able to determine the authenticity of the source network. This means that the PLMN-ID / SNPN-ID of the NFc shall be verified during service access authorization, ensuring that NFc belongs to a trusted network.For this requirement to be fulfilled, the communication networks of NFc and NFp comprise a Security Edge Protection Proxy (SEPP) at an edge of each network dedicated to handling e2e Core Network Interconnection Security. Being situated at the edge of a network means that the SEPP is placed at the boundary of a network operator’s domain. This placement allows the SEPP to perform its roles effectively, including ensuring secure and trusted inter-operator communication, managing and controlling network traffic at the boundary, facilitating interoperability between different network operators to mention a few. The confidentiality and / or integrity for the message elements is provided between two SEPPs of the source and destination PLMN / SNPN. The SEPP residing in PLMN / SNPN where the NFp is located is referred to as pSEPP while the SEPP residing in PLMN / SNPN where the NFc is located is referred to as cSEPP.In 3GPP Rel-15, the verification of the NFc PLMN-ID (or SNPN-ID) during service access authorization is based on the access token claim as described in clause 13.4.1.2.2 of 3GPP TS 33.501 (V17.14.0). Clause 13.4.1.2.2 of 3GPP TS 33.501 (V17.14.0) shows the service request process in a roaming scenario. Typically, an NFc, residing in a vPLMN (or a vSNPN) requests access to a service from an NFp residing in a hPLMN (or a hSNPN). The complete service request as disclosed in clause 13.4.1.2.2 of 3GPP TS 33.501 (V17.14.0) shows a two-step process including the NFc obtaining an access token for the service and then verifying theaccess token by the NFp. The claims in the obtained access token include a subject claim with the PLMN-ID (or SNPN-ID) of the NWp network and an audience claim with the PLMN-ID (or SNPN-ID) of the NWc network. After obtaining the access token, the NFc requests service from the NFp. The service request may contain the PLMN-ID (or SNPN-ID) of the NFc network and includes the obtained access token. The NFp verifies the access token and checks that the PLMN-ID (or SNPN-ID) contained in the API request, i.e., in the service request, is equal to the one inside the access token. The pSEPP checks that the serving PLMN-ID of subject claim in the access token matches the remote PLMN-ID. If the peer network is an SNPN, the pSEPP checks if the SNPN-ID of the NFc in the access token matched the SNPN- ID of the peer network. If the service access authorization is successful, the NFp executes the requested service and responds back to the NFc.Starting from 3GPP Rel-17, NFc PLMD-ID check based on 3gpp-Sbi-Originating-Network-Id header has been introduced. As explained in clause 5.9.3.5 of3GPP TS 33.501 (V17.14.0), an NF sending a signalling message such as service / subscription request or notification message shall include its PLMS ID or SNPN ID in a 3gpp-Sbi-Originating-Network-Id header. The PLMS ID or SNPN ID in the 3gpp-Sbi-Originating-Network-Id header is thereby asserted. The 3gpp-Sbi-Originating-Network-Id header contains the PLMN ID of the source PLMN or the SNPN ID of the source SNPN of the signalling message. If an NF supports multiple PLMN IDs or SNPN IDs, the sending NF shall include the PLMN ID or SNPN ID in the 3gpp-Sbi- Originating-Network-Id header on behalf of which the message is sent. The handling of the PLMN ID or SNPN ID in the 3gpp-Sbi-Originating-Network-Id header at the receiving NF is up to configuration and deployment. A misconfigured PLMN ID or SNPN ID in the 3gpp-Sbi- Originating-Network-Id header can lead to service interruption.As specified in 3GPP TS 33.501 (V17.14.0), clause 5.9.2.4, if the signaling message (e.g., a service / subscription request, a notification message) from the sending NF does not include the PLMN ID or SNPN ID in the 3gpp-Sbi-Originating-Network-Id header and a Service Communication Proxy (SCP) forwarding the message towards a receiving NF can determine the PLMN ID or SNPN ID value to be included in the 3gpp-Sbi-Originating-Network-Id header, the sending SCP should include it.As specified in clause 5.9.3.2 of 3GPP TS 33.501 (VI 7.14.0), if the sending NF or the SCP has inserted the 3gpp-Sbi-Originating-Network-Id header in the signaling message (e.g., a service / subscription request, a notification message), the sending SEPP shall compare the PLMN ID or SNPN ID in the 3gpp-Sbi-Originating-Network-Id header in the received signaling message with the PLMN ID(s) or SNPN ID(s) that the sending SEPP represents by its certificate.If the PLMN ID or SNPN ID does not match with any of the PLMN IDs that the sending SEPP represents, the sending SEPP shall discard the received signaling message.If the PLMN ID or SNPN ID matches with any of the PLMN IDs that the sending SEPP represents, the sending SEPP shall forward the signaling message to the receiving SEPP. If the sending NF and the SCP have not included the 3gpp-Sbi-Originating-Network-Id header in the signalling message, the sending SEPP shall include the 3gpp-Sbi-Originating-Network-Id header and send the updated signaling message to the receiving SEPP. If the sending SEPP only represents one PLMN ID or SNPN ID, the sending SEPP shall insert the 3gpp-Sbi- Originating-Network-Id header with this ID. If the sending SEPP represents multiple PLMN IDs or SNPN IDs, it is up to configuration and deployment to determine which PLMN ID or SNPN ID value should be included in the header.The receiving SEPP and NFp verifies whether the PLMN ID in the access token and / or the 3gpp-Sbi-Originating-Network-Id header matches the PLMN ID of the originating NFc (the NF sending the message). The receiving SEPP will verify whether the 3gpp-Sbi-Originating- Network-Id header included in the signalling message belongs to the sending SEPP’s own PLMN or SNPN. It does this by verifying that the asserted PLMN ID in the 3gpp-Sbi- Originating-Network-Id header matches one of the sending SEPP's own PLMN ID(s) or SNPN ID(s) either in the N32-f context, the sending SEPP's certificate, or a locally configured list of PLMN IDs or SNPN-IDs that the sending SEPP represents.If the service access authorization is successful, the NFp executes the requested service and responds back to the NFc.Equivalent PLMN / SNPN IDs.In certain Mobile Operator Networks, multiple PLMN-IDs may be defined. Typically, one large network may consist of multiple regional networks with a different PLMN-ID per eachregional network. All these regional network PLMN-IDs are equivalent PLMN-IDs of the network.When an operator of such network has contracted a roaming agreement with an operator of another network, all the equivalent PLMN-IDs of the network will be considered valid under the same roaming agreement. In other words, all equivalent PLMN-IDs may be used to identify the PLMN. The same applies to SNPN with multiple, equivalent SNPN IDs.As previously explained network entities communicating with each other may belong to different communication networks. In the context of the invention such different communication networks have different network identifiers. This means that different networks having equivalent network identifiers, don’t have any network identifiers in common.Service Based interface definition.AnNFc may specify one or multiple PLMN / SNPN IDs when requesting an access token. When the NFc is serving a PLMN consisting of one PLMN-ID, the request body of the access token request comprises the attribute "requesterPlmn" specifying the PLMN-ID. Otherwise, if the NFc is serving a PLMN consisting of more than one PLMN ID, the request body of the access token request comprises the attribute "requesterPlmnList" specifying all the PLMN-IDs of the PLMN where the NFc resides. In similar fashion, if the NFc resides in a SNPN consisting of more than one SNPN IDs, the attribute “requesterSnpnLisf ’ shall be used in the request body of the access tokes request specifying all the SNPN IDs of the SNPN where the NFc resides. However, only one PLMN / SNPN ID may be included in the access token claims (see attributes “consumerPlmnld” and “consumerSnpnld” of the access token claims.The following text from 3GPP TS 29.510 Network Function Repository Services (v!7.14.0) describes an NRF Service Based API comprising the above-mentioned attributes "requesterPlmn", "requesterPlmnList", and “requesterSnpnLisf’ that may be used in the request body of the access token request as well as the attributes “consumerPlmnld” and “consumerSnpnld” used in access toke claims.*** Begin text from 3GPP TS 29.510 (v!7.14.0)***6.3.5.2.2 Type: AccessTokenReqTable 6.3.5.2.2-1 : Definition of type AccessTokenReq.3.5.2.4 Type: AccessTokenClaimsTable 6.3.5.2.4-1 : Definition of type AccessTokenClaims*** End text from 3GPP TS 29.510 (V17.14.0) ***The 3gpp-Sbi-Originating-Network-Id header can only carry one PLMN / SNPN ID for each signalling message.The following text from 3GPP TS 29.500 (vl 8.6.0), Technical Realization of Service Based Architecture (VI 8.6.0) describes the characteristics of the 3gpp-Sbi-Originating-Network-Id header.***Start text from 3GPP TS 29.500 (vl8.6.0) ***5.2.3.2.15 3gpp-Sbi-Originating-Network-IdThe header contains the PLMN Identity (MCC-MNC) of the source PLMN or the SNPN ID (MCC-MNC -NID) of the source SNPN of the received HTTP messages.The encoding of the header follows the ABNF as defined inIETF RFC 9110

[0011] ,srcinfo = " arc" " : " RWS srctype srcfqdn srctype = " SCP" / " SEPP" srcfqdn = 4 * ( ALPHA / DI GI T / "-" / " . " )The srcinfo shall only be present when SCP or SEPP was unable to uniquelydetermine the value, i.e. PLMN ID, and has decided to insert the header with the value derived by configuration as described in Table 5.2.3.2.1-1.The srcfqdn shall indicate FQDN of SCP or SEPP that inserted the header when srcinfo is present.EXAMPLE 1 : For a source PLMN :3gpp-Sbi-Originating-Network-Id: 123-45EXAMPLE 2: For a source PLMN and the header included by SEPP under the condition when the value of the header is derived based on the configuration and inserted by the SEPP: 3gpp-Sbi-Originating-Network-Id: 123-45: src: SEPP- seppOO 1. sepp .5gc.mnc045.mcc 123.3 gppnetwork. orgEXAMPLE S: For a source SNPN:3gpp-Sbi-Originating-Network-Id: 123-45-000007ed9d5***End text from 3GPP TS 29.500 (vl8.6.0) ***There currently exist certain challenges. When anNFc residing in a PLMN or a SNPN network with equivalent PLMN / SNPN IDs interworks with an NFp residing in another network, the PLMN ID verification may fail in different scenarios and lead to service interruption. Fig. la and Fig. lb illustrate some different scenarios where the PLMN ID verification during service request process fails leading to service interruption.Fig. la and Fig. lb each shows a signalling diagram of an exemplary service request process involving an NFc requesting a service from an NFp.The service request process illustrated in Fig. la involves an NFc requesting a service from an NPp. The NFc is located in a 3GPP Rel. 16 PLMN and is registered with the cNRF. The PLMN of NFc has equivalent PLMN IDs PLMN1 and PLMN2. As previously explained, both PLMN IDs PLMN1 and PLMN2 may be used to identify the PLMN of NFc. The NFp is located in a 3GPP Rel. 16 PLMN, different from the PLMN of the NFc, and is registered with the pNRF. In the communication between the two PLMN, security is enabled by the SEPPs of both networks, cSEPP and pSEPP in Fig la.In operation 1, the NFc wishing to obtain a service from NFp requests an access token for the service. The token may be requested by sending an Nnrf_AccessToken_Get Request to the authorization server cNRF serving the NFc. The token request comprises different parametersas described in clause 13.4.1.2.2. of 3GPP TS 33.501 (V17.14.0), such as e.g., the PLMN IDs of the PLMN of the NFc, i.e., PLMN1 and PLMN2 as well as the PLMN IDs of the PLMN of the NFp.In operation 2, the authorization server cNRF identifies the NRF in the PLMN of the NFp (i.e., the pNRF) based on the PLMN ID of the NFp PLMN, and request an access token from pNRF as described in clause 4.17.5 of TS 23.502, Procedures for the 5G System (5GS) (v!7.12.0). The cNRF forwards the parameters it obtained from the NFc, including PLMN1 and PLMN2.In operations 3 and 4 the cSEPP and the pSEPP forwards the access token request to the pNRF. The pNRF checks whether the NFc is authorized to access the requested service(s). If the NFc is authorized, the pNRF shall generate an access token with appropriate access token claims included as defined in clause 13.4.1.1 of 3GPP TS 33.501 (VI 7. 14.0). The claims in the access token comprise PLMN ID of the NFc PLMN. As previously mentioned, only one PLMN ID of the NFc PLMN can be included in the access token claims. When the NFc provides multiple PLMN IDs in the access token request to pNRF, the pNRF does not know which PLMN ID should be included in the access token. In the exemplary process illustrated in Fig. la, the NRF may select either PLMN ID 1 or PLMN 2 depending on NRF implementation. As a possible example, in Fig la it is assume that PLMN ID 1 is included in the access token.In operations 5-8 the access token is transmitted to the cNF, e.g., by including the access token in an Nnrf_AccessToken_Get Response.In operation 9, the NFc requests the service from the NFp e.g., by sending an NF Service Request towards the NFp. The service request includes the access token received by the NFc in operation 8. The service request may also comprise a PLMN-ID of the NFc as determined by the RAN when UE is connected. The information of PLMN ID is identified by the tracking area identifier (TAI) of the gNodeB (gNB) that the UE is connected to. The TAI is carried in almost all Non-Access Stratum (NAS) signalling messages sending from RAN to Access and Mobility Management Function (AMF). And AMF will use this received PLMN ID for further processing towards other NFs in the 5GC. In Fig. la it is assumed that the UE is connected from TAI= PLMN2, thus PLMN ID PLMN2 is included in the service request message.In operations 10 and 11 the service request is forwarded by cSEPP to the terminating SEPP (pSEPP) and further to the NFp. The terminating SEPP and NFp verify whether the PLMN ID in the access token matches the PLMN ID of the NFs (the NF sending the message). The terminating SEPP verifies whether the PLMN ID in the access token matches the remote PLMN ID in e.g., a PLMN ID list, for example from N32-f context for PRINS scenario as specified in the clause 13.4.1.2.2 of TS 33.501 (or from TLS certificate of cSEPP for non- PRINS scenario). In the scenario illustrated in Fig. la, the valid / authorized remote PLMN ID is either PLMN 1 or 2. Since the PLMN id in the access token matches the valid / authorized remote PLMN ID the verification made by the terminating SEPP will be successful.The NFp verifies whether the PLMN ID in the access token matches the PLMN ID of the NFc (the NF sending the message) contained in the API request. In the scenario shown in Fig. la, the PLMN-ID of the NFc PLMN in the API request does not match with the PLMN ID the NFc PLMN in the access token claim. The access token-based verification of the NFc PLMN ID will therefore fail leading to service interruption.Fig. lb illustrates a similar network scenario as that of Fig.la. with the difference that the NFc PLMN and the NFp PLMN are both Rel-17 NFc networks. As previously described, the verification of NFc PLMD-ID may here therefore be done based on 3gpp-Sbi-Originating- Network-Id.Operations 1-8 show the NFc requesting and receiving an access token for a service corresponding to the operations 1-8 in Fig. la.In operation 9, the NFc requests the service from the NFp as described in operation 9 with reference to Fig. la.In operation 10, the sending SEPP (cSEPP) forwards the service request from NFc towards the NFp. When the NFc doesn't include a 3gpp-Sbi-Originating-Network-Id header in the message, the sending SEPP will insert the header on behalf of the NFc. If the sending SEPP represents multiple PLMN IDs or SNPN IDs, it is up to configuration and deployment to determine which PLMN ID or SNPN ID value is included in the header. Thus, the sending SEPP may include in the header an PLMN / SNPN ID mismatching the PLMN ID of the service message (e.g. amessage to update a PDU session of a UE from a certain PLMN). As previously described, the 3gpp-Sbi-Originating-Network-Id header may only comprise one PLMN ID.

[0001] In operations 11 and 12, the service request is forwarded, via the terminating SEPP (pSEPP) to the NFp. The terminating SEPP verifies whether the PLMN ID in the HTTP header matches the PLMN ID of the sending SEPP, either in the N32-f context, the sending SEPP's certificate, or a locally configured list of PLMN IDs that the sending SEPP represents.The handling of the PLMN ID in the 3gpp-Sbi-Originating-Network-Id header at the receiving NF is up to configuration and deployment. A misconfigured PLMN ID in the 3gpp-Sbi- Originating-Network-Id header can lead to service interruption. In the shown scenario the PLMN ID in the 3gpp-Sbi-Originating-Network-Id header does not match the PLMN ID included in the service message. The 3gpp-Sbi-Originating-Network-Id header-based verification of the NFc PLMN ID will therefore fail leading to service interruption.SUMMARYCertain aspects of the disclosure and their embodiments may provide solutions to these or other challenges. Embodiments of the present disclosure advantageously enable PLMN / SNPN ID verification with equivalent PLMN / SNPN IDs in particular when an NFc residing in a PLMN or SNPN network with equivalent PLMN / SNPN IDs wishes to access a service provided by an NFp in another network.The disclosure herein provides for an extension of the Service Based API definition related to the access token and a 3gpp-Sbi-Originating-Network-Id header such that the access token and the 3gpp-Sbi-Originating-Network-Id header are enabled to carry equivalent PLMN / SNPN IDs.In particular, the disclosure proposes the following additions to 3 GPP security requirements: The NRF shall include the equivalent PLMN / SNPN IDs in access token, if the NFc provides multiple PLMN / SNPN IDs in the access token request.The SCP or sending SEPP when inserting the 3gpp-Sbi-Originating-Network-Id header shall include the equivalent PLMN / SNPN IDs, if the serving network supports multiple equivalent PLMN / SNPN IDs.When performing PLMN / SNPN verification, the receiving / terminating SEPP / NFp shall verify the PLMN / SNPN ID of the originating NFc against the PLMN ID and all equivalent PLMN / SNPN IDs. I.e., the message will be rejected only when the PLMN / SNPN ID of the message does not match all the PLMN / SNPN IDs in the access token / 3gpp-Sbi-Originating- Network-Id.Embodiments of the current disclosure provide techniques whereby the access token claim is extended to allow carrying the equivalent PLMN / SNPN IDs. Moreover, the disclosure proposes an NRF enabled to include the equivalent PLMN / SNPN IDs in the access token claims when an NFc includes multiple PLMN / SNPN IDs in the access toke request.Embodiments of the current disclosure provide techniques whereby the 3gpp-Sbi-Originating- Network-Id header is extended to allow carrying the equivalent PLMN / SNPN IDs. Embodiments of the current disclosure provides techniques whereby an SCP and a sending SEPP are enabled to include the equivalent PLMN / SNPN IDs when inserting the 3gpp-Sbi- Originating-Network-Id header.Embodiments of the current disclosure provide techniques whereby a SEPP and an NFp are enabled to perform PLMN / SNPN verification towards all PLMN / SNPN IDs (including the equivalent PLMN / SNPN IDs).Certain embodiments may provide one or more of the following technical advantages. Embodiments of the present disclosure may enhance the mechanism of PLMN / SNPN verification for a network with multiple equivalent PLMN / SNPN IDs. The enhancement may allow the PLMN / SNPN verification against all equivalent PLMN / SNPN IDs, to avoid an unexpected service message rejection due to PLMN / SNPN ID mismatching while fulfilling the 3GPP security requirements.ADDITIONAL EXPLANATIONSome of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. Embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art.In general, the discussion below is provided in the context of a Fifth Generation (5G) wireless communication network. Notwithstanding, those skilled in the art will appreciate that the techniques and solutions provided below are not limited in their applicability to 5G networks. Indeed, many of the teachings provided below may also be used in wireless communication networks operating according to other standards. In particular, the embodiments described below may be particularly well suited for (but not limited to) derivatives of, and / or successors to, 5G networks, for example. Other embodiments may additionally or alternatively be used in predecessor Third Generation Partnership Project (3GPP) networks.Fig. 2 illustrates an example communication network 10 that is consistent with the 3 GPP 5G system architecture. The communication network 10 comprises a radio access network (RAN) 20 and a core network 30 employing a service-based architecture. The service-based architecture for the 5G Core (5GC) was defined in 3GPP Release 15, has evolved in later releases, and may continue to evolve in future releases. The RAN 20 and the core network 30, when operated by the same operator, are sometimes collectively referred to as a Public Land Mobile Network (PLMN) or Standalone Non-Public Network (SNPN) of the operator. Although several examples below will be described in terms of PLMNs, it should be understood that other embodiments instead involve SNPNs and that similar principles will apply.The RAN 20 comprises one or more base stations 25 that are configured to provide radio access to one or more UEs 100 operating within a coverage area of the PLMN. In the context of certain 5G networks, a base station 25 may be referred to as a gNodeBs (gNB). The core network 30 provides a connection between the RAN 20 and one or more data networks (DNs) 90, such as the Internet, for example. In this example, the communication network 10 includes a Visited PLMN (VPLMN) that provides a local breakout to the DN 90. That said, in other examples to be discussed in greater detail below, the PLMN of particular embodiments may instead provide a home-routed user plane to a Home PLMN (HPLMN) where a breakout to the DN 90 occurs.The core network 30 comprises a plurality of network functions (NFs). These NFs may be in either the user plane 33 or the control plane 37 of the core network 30. The user plane 33 (sometimes referred to as the data plane) typically carries user data traffic. The control plane 37 typically carries signaling traffic (e.g., control packets).In this example, the NFs of the user plane 33 comprise a User Plane Function (UPF) 35. The NFs of the control plane 37 comprise an Access and Mobility Management Function (AMF) 40, a Session Communication Proxy (SCP) 42, a Session Management Function (SMF) 45, a Network Slice Specific Authentication and Authorization Function (NSSAAF) 47, a Policy Control Function (PCF) 50, a Unified Data Management (UDM) function 55, a Unified Data Repository (UDR) function 57, an Authentication Server function (AUSF) 60, a Network Data Analytics Function (NWDAF) 65, a Network Exposure Function (NEF) 70, a Network Repository Function (NRF) 75, and a Network Slice Selection Function (NSSF) 80. The control plane 37 of the core network 30 also includes an Application Function (AF) 85, and a Security Edge Protection Proxy (SEPP) 95.The SEPP 95 is a proxy for control plane messages configured to protect the edge of an operator network. Among other things, the SEPP 95 may be configured to protect control plane signaling between network operators, hide the network topology from other networks, and / or filter control plane messages exchanged in support of roaming scenarios. In particular a SEPP 95 may be referred to based on whether the SEPP 95 is on the service consumer side or the service provider side. In this regard, a SEPP 95 on the service consumer side may be referred to as a cSEPP whereas a SEPP 95 on the service provider side may be referred to as a pSEPP. In general, when the SEPPs of different networks first interact, the vSEPP is likely to be cSEPP, whereas the hSEPP is likely to be a pSEPP. That said, once the SEPPs of the two networks are known to each other, either SEPP may be a cSEPP or a pSEPP for subsequent interactions between the two. The vSEPP and the hSEPP communicate with each other over an N32 interface. The N32 interface may include an N32-c interface for negotiating security capabilities between SEPPs and an N32-f interface for data plane signaling (e.g., encrypted messages between PLMNs 10).The NFs of the core network 30 comprise logical entities that reside in one or more core network nodes, which may be implemented using computing hardware, such as one or more processors, memory, network interfaces, or a combination thereof. The functions may reside in a single core network node or may be distributed among a plurality of core network nodes. The NFs may communicate with one another using predefined interfaces.Application Function (AF, with Naf interface) interacts with the 5GC to provision information to the network operator and to subscribe to certain events happening in operator's network. An AF offers applications for which service is delivered in a different layer (i.e., transport layer) than the one in which the service has been requested (i.e., signaling layer), the control of flow resources according to what has been negotiated with the network. An AF communicates dynamic session information to PCF (via N5 interface), including description of media to be delivered by transport layer.Policy Control Function (PCF, with Npcf interface) supports unified policy framework to govern the network behavior, via providing PCC rules (e.g., on the treatment of each service data flow that is under PCC control) to the SMF via the N7 reference point. PCF provides policy control decisions and flow based charging control, including service data flow detection, gating, QoS, and flow-based charging (except credit management) towards the SMF. The PCF receives session and media related information from the AF and informs the AF of traffic (or user) plane events.User Plane Function (UPF) supports handling of user plane traffic based on the rules received from SMF, including packet inspection and different enforcement actions (e.g., event detection and reporting). UPFs communicate with the RAN (e.g., NG-RNA) via the N3 reference point, with SMFs (discussed below) via the N4 reference point, and with an external packet data network (PDN) via the N6 reference point. The N9 reference point is for communication between two UPFs.Session Management Function (SMF, with Nsmf interface) interacts with the decoupled traffic (or user) plane, including creating, updating, and removing Protocol Data Unit (PDU) sessions and managing session context with the User Plane Function (UPF), e.g., for event reporting.For example, SMF performs data flow detection (based on filter definitions included in PCC rules), online and offline charging interactions, and policy enforcement.Charging Function (CHF, with Nchf interface) is responsible for converged online charging and offline charging functionalities. It provides quota management (for online charging), reauthorization triggers, rating conditions, etc. and is notified about usage reports from the SMF. Quota management involves granting a specific number of units (e.g., bytes, seconds) for a service. CHF also interacts with billing systems.Access and Mobility Management Function (AMF, with Namf interface) terminates the RAN CP interface and handles all mobility and connection management of UEs (similar to MME in EPC). AMFs communicate with UEs via the N1 reference point and with the RAN (e.g., NG- RAN) via the N2 reference point.Network Exposure Function (NEF, with Nnef interface) acts as the entry point into operator's network, by securely exposing to AFs the network capabilities and events provided by 3GPP NFs and by providing ways for the AF to securely provide information to 3 GPP network. For example, NEF provides a service that allows an AF to provision specific subscription data (e.g., expected UE behavior) for various UEs.Network Repository Function (NRF, 210, with Nnrf interface) provides service registration and discovery, enabling NFs to identify appropriate services available from other NFs.Network Slice Selection Function (NSSF, with Nnssf interface): A “network slice” is a logical partition of a 5G network that provides specific network capabilities and characteristics, e.g., in support of a particular service. A network slice instance is a set of NF instances and the required network resources (e.g., compute, storage, communication) that provide the capabilities and characteristics of the network slice. The NSSF enables other NFs (e.g., AMF) to identify a network slice instance that is appropriate for a UE’s desired service.Authentication Server Function (AUSF, with Nausf interface) performs user authentication and computes security key materials for various purposes, and is based in a user’s home network (HPLMN).Network Data Analytics Function (NWDAF with Nnwdaf interface) provides network analytics information (e.g., statistical information of past events and / or predictive information) to other NFs on a network slice instance level.Location Management Function (LMF, with Nlmf interface) supports various functions related to determination of UE locations, including location determination for a UE and obtaining any of the following: DL location measurements or a location estimate from the UE; UL location measurements from the NG RAN; and non-UE associated assistance data from the NG RAN.Unified Data Management function (UDM, with Nudm interface) supports generation of 3GPP authentication credentials, user identification handling, access authorization based on subscription data, and other subscriber-related functions. To provide this functionality, the UDM uses subscription data (including authentication data) stored in the 5GC unified data repository (UDR). In addition to the UDM, the UDR supports storage and retrieval of policy data by the PCF, as well as storage and retrieval of application data by NEF.The services provided by the various NFs are composed of “service operations”, which are more granular divisions of the overall service functionality. The interactions between service consumers and producers can be of the type “request / response” or “subscribe / notify”. In the latter type, a service consumer NF (or equivalently, “consumer NF”) requests a service producer NF (or equivalently, “producer NF”) to establish a subscription for the service consumer NF to receive notifications from the service producer NF under conditions specified in this subscription.Fig. 3 shows a simplified signaling diagram of a service request procedure involving an NFp requesting a service from an NFc according to various embodiments of the present disclosure. The full service request procedure is described in clause 13.4.1.2.2 of 3GPP TS 33.501 (V17.14.0). Fig. 3 only show operations which are important for understanding the embodiments of the disclosure. The service request procedure includes obtaining an access token by the NFc for a service provided by an NFp in operations 1-3 and then performing by the NFp a service access request based on token verification in operations 5-7. Although theoperations shown in Fig. 3 are given numerical labels, this is intended to facilitate explanation rather than to require or imply any specific operational order, unless stated otherwise below.In operation 1 of Fig. 3, the NFc requests NRF to provide an Access Token. When the NFp and the NFc belong to different communication networks such as a first communication network, (NW1) 302 and a second communication network (NW2) 304, the access token is generated by the NFR in the NFp communication network as explained in clause 13.4.1.2.2 of 3GPP TS 33.501 (V17.14.0). The access token request is performed by the NFc invoking a Nnrf_AccessToken_Get Service Operation. When the NFc belongs to a communication network, such as a PLMN or a SNPN, having a plurality of equivalent network identifiers, the access token request includes the plurality of equivalent network identifiers.In operation 2 of Fig. 3, the NRF generates an access token with appropriate access token claims according to the access token request. In embodiments, when the NFc belongs to a communication network having a plurality of equivalent network identifiers, the access token claims include the includes the plurality of equivalent network identifiers.In operation 3 on Fig. 3, the NRF sends the access token with the claims including the plurality of equivalent network identifiers of the NFc communication network to the NFc.The following text describes the Nnrf_AccessToken_Get Service Operation according to embodiments of the disclosure. The text is based on the clause 14.3.2 of TS 3GPP TS 33.501 (V17.14.0) and updated according to some embodiment of the current disclosure. The updated parts are underlined.***Start text impacts to 3GPP TS 33.501***14.3.2 Nnrf_AccessToken_Get Service OperationService Operation name: Nnrf_AccessToken_Get.Description: NF Service Consumer requests NRF to provide an Access Token.Inputs, Required: the NF Instance Id of the NF Service Consumer, the requested "scope" including the expected NF service name(s).Inputs, Optional: PLMN ID(s) (or SNPN ID(s)) of the requester NF Service Consumer, PLMN ID (or SNPN ID) of the requested NF Service Producer, NF Instance Id(s) of the requested NF Service Producer, NF type of the expected NF Service Producer instance and NF Service Consumer, "additional scope" information (i.e. requested resources and requested actions (service operations) on the resources), list of NSSAIs or list of NSI IDs for the expected NF Service Producer instances, NF Set ID of the expected NF Service Producer instances, list of S-NSSAIs of the NF Service Consumer.Outputs, Required: Access Token with appropriate claims, where the claims shall include NF Instance Id of NRF (issuer), NF Instance Id of the NF Service Consumer potentially appended with its PLMN ID(s) (or SNPN ID(s)) (subject), NF type of the NF Service Producers or NF Instance Id or several NF Instance Id(s) of the requested NF Service Producer, potentially appended with PLMN ID (or SNPN ID) (audience), expected service name (scope), optionally "additional scope" information (allowed resources and allowed actions (service operations) on the resources) and expiration time (expiration), may include list of NSSAIs or NSI IDs for the expected NF Service Producer instances, and may include the NF Set ID of the expected NF Service Producer instances.Outputs, Optional: None.***End text impacts to 3GPP TS 33.501***To enable an addition of equivalent network identifiers of a communication network in the access token claims according to embodiments of the present disclosure, two new attributes are added to the Service Based API definition of access token claims:- “consumerEquivalentPlmnldLisf ’ allowing adding multiple PLMN-IDs to the access token claims when the communication network of the NFc is a PLMN having a plurality of equivalent network identifiers, and- “consumerEquivalentSnpnldList” allowing adding multiple SNPN-IDs to the access token claims when the communication network of the NFc is a SNPN having a plurality of equivalent network identifiers.The following text describes impacts to the API definition of access token claims described in Table 6.3.5.2.4-1 of 3GPP TS 29.510 (vl7.14.0) according to embodiments of the disclosure. The updated / added parts are underlined.***Start text impacts to 3GPP TS 29.510***Table 6.3.5.2.4-1 : Definition of type AccessTokenClaims***End text impacts to 3GPP TS 29.510***Referring back to Fig.3, in operation 4, The NFc requests service from the NFp. The service request includes the access token received by the NFc in operation 3.As previously explained, the service request may, in embodiments, additionally comprise a 3gpp-Sbi-Originating-Network-Id header. The 3gpp-Sbi-Originating-Network-Id header may be included in the service request message by the NFc. If not included by the NFc, the header may be included in the service request message by a SCP or by the cSEPP forwarding the service request. In embodiments, when the NFc belongs to a communication network having a plurality of equivalent network identifiers, the 3gpp-Sbi-Originating-Network-Id header includes the plurality of equivalent network identifiers.The following text describes impacts to the definition of the 3gpp-Sbi-Originating-Network-Id header in Table 5.2.3.2.1-1 of TS 29.500 (vl8.6.0) according to embodiments of the present disclosure, enabling the 3gpp-Sbi-Originating-Network-Id header to carry the plurality of equivalent network identifiers. The updated / added parts are underlined.***Start text impacts to 3GPP TS 29.500 (vl8.6.0) ***5.2.3.2.1 GeneralThe 3GPP NF Services shall support the HTTP custom headers specified in Table 5.2.3.2.1-1 below. A description of each custom header and the normative requirements on when toinclude them are also provided in Table 5.2.3.2-1.Table 5.2.3.2.1 -1 : Mandatory HTTP custom headers5.2.3.2.15 3gpp-Sbi-Originating-Network-Id The header contains the PLMN Identity (MCC-MNC) of the source PLMN or the SNPN ID (MCC-MNC-NID) of the source SNPN of the received HTTP messages.The encoding of the header follows the ABNF as defined in IETF RFC 9110 [ll],Sbi-Originating-Network-Id-Header = "3gpp-Sbi-Originating-Network-Id:" OWS2*3DIGIT [ 11HEXDIG ] [ OWS srcinfo ] 1 OWS equivalent-network-ids 1 OWS srcinfo = "src" RWS srctype "-" srcfqdn srctype = "SCP" / "SEPPsrcfqdnequivalent-network-ids = "eq-nw-ids=" 3DIGIT 2*3DIGIT [ 11HEXDIG 1 1*[RWS 3DIGIT "-" 2*3DIGIT [ "-" 11HEXDIG 11The srcinfo shall only be present when SCP or SEPP was unable to uniquely determine the value, i.e., PLMN ID, and has decided to insert the header with the value derived by configuration as described in Table 5.2.3.2.1-1.The srcfqdn shall indicate FQDN of SCP or SEPP that inserted the header when srcinfo is present.The equivalent-network-ids shall be present when the header is inserted by the SCP or SEPP, while SCP or SEPP was unable to uniquely determine the value, i.e. the PLMN / SNPN ID, and the originating network is configured with equivalent network IDs.EXAMPLE 1 : For a source PLMN:3gpp-Sbi-Originating-Network-Id: 123-45EXAMPLE 2: For a source PLMN and the header included by SEPP under the condition when the value of the header is derived based on the configuration and inserted by the SEPP:3gpp-Sbi-Originating-Network-Id: 123-45; src: SEPP- seppOO 1. sepp.5gc. mnc045.mcc 123.3gppnetwork. orgEXAMPLE 3: For a source SNPN:3gpp-Sbi-Originating-Network-Id: 123-45-000007ed9d5EXAMPLE 4: For a source PLMN and the header included by SEPP under the condition when the value of the header is derived based on the configuration and inserted by the SEPP, and the PLMN has been configured with equivalent PLMN IDs:_ 3gpp-Sbi-Originating-Network-Id: 123-45; src: SEPP- seppOO 1. sepp.5 gc. mnc045 ,mcc 123,3 gppnetwork, org; eq-nw-ids= 123-46 123-47***End text impacts to 3GPP TS 29.500 (vl8.6.0) ***In operation 5 in Fig. 3, the service request is verified. The verification comprises verification of the PLMN-ID (or SNPN ID) of the serving network, i.e., the PLMN-ID (or SNPN ID) of the NFc communication network. When the service request comprises an 3gpp-Sbi- Originating-Network-Id header, the verification of the PLMN-ID (or SNPN ID) of the serving network may be done based on the PLMN ID (or SNPN ID) contained in the access tokenand / or on the PLMN ID (or SNPN ID) in the 3gpp-Sbi-Originating-Network-Id header. When the service request does not comprise an 3gpp-Sbi-Originating-Network-Id header, the verification of the PLMN-ID (or SNPN ID) of the serving network is done based on the PLMN ID (or SNPN ID) contained in the access token.In embodiments, a verification of the PLMN-ID (or SNPN ID) of the serving network based on the access token comprises, the NFp verifying that the PLMN-ID (or SNPN ID) of the serving network contained in the API request is equal to one PLMN ID of the NF Service Consumer contained in the one inside the access token.In embodiments, when the access token claims comprise a plurality of equivalent network identifiers of the NFc communication network, the pSEPP, i.e., the SEPP of the communication network of the NFp, checks that the serving PLMN ID(s) of subject claim, i.e., the plurality of equivalent network identifiers of the NFc communication network in the access token matches the remote PLMN ID. If PRINS is used, this can be achieved by the pSEPP checking that at least one PLMN ID of the serving network in the access token matches one of the remote PLMN ID(s) in the N32-f context. If TLS is used, this can be achieved by the pSEPP checking that at least one PLMN ID of the serving network in the access token matches one of the PLMN ID(s) in the remote TLS certificate.If the peer network is an SNPN, the pSEPP checks that at least one SNPN ID(s) of the NFc in the access token matches one of the SNPN ID of the peer network.In addition, the NFp shall verify that the PLMN-ID (or SNPN ID) of the serving network contained in the API request is equal to at least one PLMN ID of the NF Service Consumer contained in the access token.The following text describes impacts to the description of the service request process in clause 13.4.1.2.2 of TS 33.501 according to embodiments of the present disclosure, enabling verification of the NFc communication network comprising a plurality of equivalent network identifiers. The updated / added parts are underlined.***Start text impacts to 3GPP TS 33.501***13.4.1.2.2 Service Request ProcessIn addition to the steps described in the non-roaming scenario in 13.4. 1. 1, the NF Service Producer shall verify that the PLMN-ID (or SNPN ID) of the serving network contained in the API request is equal to one PLMN ID of the NF Service Consumer contained in the one inside the access token.The pSEPP shall check that the serving PLMN ID(s) of subject claim in the access token matches the remote PLMN ID. If PRINS is used, this can be achieved by the pSEPP checking that at least one PLMN ID of the serving network in the access token matches one of the remote PLMN ID(s) in the N32-f context. If TLS is used, this can be achieved by the pSEPP checking that at least one PLMN ID of the serving network in the access token matches one of the PLMN ID(s) in the remote TLS certificate.If the peer network is an SNPN, the pSEPP shall check that at least one SNPN ID(s) of the NF Service Consumer in the access token matches one of the SNPN ID of the peer network.***End text impacts to 3GPP TS 33.501***In embodiments, a verification of the PLMN-ID (or SNPN ID) of the serving network based on the 3gpp-Sbi-Originating-Network-Id header comprises the receiving SEPP, i.e., the pSEPP, checking whether the 3gpp-Sbi-Originating-Network-Id header included in the service request belongs to the sending SEPP’s own PLMN or SNPN. It does this by verifying that the asserted PLMN ID or at least one of equivalent PLMN / SNPN IDs in the 3gpp-Sbi-Originating- Network-Id header matches one of the sending SEPP's own PLMN ID(s) or SNPN ID(s) either in the N32-f context, the sending SEPP's certificate, or a locally configured list of PLMN IDs or SNPN-IDs that the sending SEPP represents.If the 3gpp-Sbi-Originating-Network-Id header does not match with any of the PLMN IDs or SNPN IDs belonging to the peer sending SEPP, the receiving SEPP discards the received signaling message.If the 3gpp-Sbi-Originating-Network-Id header matches with any PLMN ID of the PLMN or SNPN IDs belonging to the peer sending SEPP, the header is successfully verified, and the receiving SEPP shall forward the received signaling message to the target NFp.Upon reception of the signaling message from the receiving SEPP, the NFp verifies the sending network by verifying if the PLMN-ID (or SNPN ID) of the serving network contained in the API request is equal to the asserted PLMN / SNPN ID or at least one of equivalent PLMN / SNPNIDs in the 3gpp-Sbi-Originating-Network-Id header. Thus, if the PLMN-ID (or SNPN ID) of the serving network contained in the API request is equal to the asserted PLMN / SNPN ID or at least one of equivalent PLMN / SNPN IDs in the 3gpp-Sbi-Originating-Network-Id header, the sending network is successfully verified.The following text describes impacts to the requirements for SEPP in clause 5.9.3.2 of TS 33.501 and to the requirements for the NE in clause 5.9.3.5 of TS 33.501 according to embodiments of the present disclosure, enabling verification of the NFc communication network comprising a plurality of equivalent network identifiers. The updated / added parts are underlined.***Start text impacts to 3GPP TS 33.501***5.9.3.2 Requirements for Security Edge Protection Proxy (SEPP):Sending SEPP behavior for the 3gpp-Sbi-Originating-Network-Id header:If the sending NF or the SCP has inserted the 3gpp-Sbi-Originating-Network-Id header in the signaling message (service / subscription request or notification message), the sending SEPP shall compare the PLMN ID or SNPN ID or equivalent PLMN / SNPN IDs in the 3gpp-Sbi-Originating-Network-Id header in the received signaling message with the PLMN ID(s) or SNPN ID(s) that the sending SEPP represents by its certificate.If the PLMN ID or SNPN ID or any one of the equivalent PLMN / SNPN IDs does not match with any of the PLMN IDs that the sending SEPP represents, the sending SEPP shall discard the received signaling message.If the PLMN ID or SNPN ID or any one of the equivalent PLMN / SNPN IDs matches with any of the PLMN IDs that the sending SEPP represents, the sending SEPP shall forward the signaling message to the receiving SEPP.If the sending NF and the SCP have not included the 3gpp-Sbi-Originating- Network-Id header in the signalling message, the sending SEPP shall include the 3gpp-Sbi- Originating-Network-Id header and send the updated signaling message to the receiving SEPP.If the sending SEPP only represents one PLMN ID or SNPN ID, the sending SEPP shall insert the 3gpp-Sbi-Originating-Network-Id header with this ID.If the network is configured with equivalent PLMN / SNPN IDs and the sending SEPP represents multiple PLMN IDs or SNPN IDs, the equivalent PLMN / SNPN IDs should be included in the Sbi-Originating-Network-Id header.Receiving SEPP behavior for the 3gpp-Sbi-Originating-Network-Id header:The receiving SEPP shall check whether the 3gpp-Sbi-Originating-Network-Id header included in the signalling message belongs to the sending SEPP’s own PLMN or SNPN. It does this by verifying that the asserted PLMN ID or at least one of equivalent PLMN / SNPN IDs in the 3gpp-Sbi-Originating-Network-Id header matches one of the sending SEPP's own PLMN ID(s) or SNPN ID(s) either in the N32-f context, the sending SEPP's certificate, or a locally configured list of PLMN IDs or SNPN-IDs that the sending SEPP represents.If the 3gpp-Sbi-Originating-Network-Id header does not match with any of the PLMN IDs or SNPN IDs belonging to the peer sending SEPP, the receving SEPP shall discard the received signaling message.If the 3gpp-Sbi-Originating-Network-Id header matches with any PLMN ID of the PLMN or SNPN IDs belonging to the peer sending SEPP, the header is successfully verified, and the receiving SEPP shall forward the received signaling message to the target NF.5.9.3.5 Requirements for Network Functions (NF):The NF that sends a signalling message (service / subscription request or notification message) shall include its PLMN ID or SNPN ID in the 3gpp-Sbi-Originating-Network-Id header.If an NF supports multiple PLMN IDs or SNPN IDs, the sending NF shall include the PLMN ID or SNPN ID in the 3gpp-Sbi-Originating-Network-Id header on behalf of which the message is sent.The receiving NF shall verify PLMN-ID (or SNPN ID) of the serving network contained in the API request is equal to the asserted PLMN / SNPN ID or at least one of equivalent PLMN / SNPN IDs in the 3gpp-Sbi-Originating-Network-Id header.The handling of the PLMN ID or SNPN ID in the 3gpp Sbi Originating Network Id header at the receiving NF is up to configuration and deployment.NOTE: - A misconfigured PLMN ID or SNPN ID in the 3gpp Sbi Originating Network Id header can lead to service interruption.***End text impacts to 3GPP TS 33.501***Upon successful service access authorization including a successful verification of the sending network as described above, NFp executes the requested service and notifies the NFc by sending a service response in operation 6 in Fig.3.These embodiments described above can be further illustrated with reference to Fig. 4 - Fig. 7 which depict exemplary methods (e.g., procedures) for an NRF, an NFc, a SCP, and to a SEPP respectively. The exemplary methods shown in Fig. 3 - Fig. 6 can be used cooperatively (e.g., with each other and with other procedures described herein) to provide benefits, advantages, and / or solutions to problems described herein. Although the exemplary methods are illustrated in Fig. 4 - Fig. 7 by specific blocks in particular orders, the operations corresponding to the blocks can be performed in different orders than shown and can be combined and / or divided into blocks and / or operations having different functionality than shown. Optional blocks and / or operations are indicated by dashed lines.More specifically, Fig. 4 illustrates an exemplary method (e.g., procedure) for an NRF of a first communication network (e.g., 5GC), according to various embodiments of the present disclosure. The exemplary method shown in Fig. 4 can be performed by an NRF or network equipment configured to implement an NRF, such as described elsewhere herein.The exemplary method includes the operations of block 410, where the NRF receives, from an NFc of a second communication network having a plurality of equivalent network identifiers, an access token request, the access token request comprising the plurality of equivalent network identifiers, wherein the access token request is a request for an access token for a service provided by an NFp of the first communication network. The exemplary method also includes the operations of block 320, where the NRF generates the access token comprising a claim with the plurality of equivalent network identifiers of the second communication network. The exemplary method also includes the operations of block 330, where the NRF sends the access token towards the NFc.In some embodiments, the first communication network and the second communication network are different communication networks.In some embodiments, the first and the second communication networks are fifth-generation (5G) mobile networks. In embodiments the first communication network and / or the second communication network is a Public Land Mobile Network (PLMN). In embodiments the first communication network and / or the second communication network is a Standalone Non-Public Network (SNPN).In addition, Fig. 5 illustrates an exemplary method (e.g., procedure) for an NFc of a second communication network (e.g., 5GC), the communication network having a plurality of equivalent network identifiers, according to various embodiments of the present disclosure. The exemplary method shown in Fig. 5 can be performed by an NFc or network equipment configured to implement an NFc, such as described elsewhere herein.The exemplary method includes the operations of block 510, where the NFc sends, to anNRF, an access token request, wherein the access token request comprises the plurality of equivalent network identifiers of the second communication network. The exemplary method also includes the operations of block 520, where the NFc receives from the NRF an access token, wherein an access token claim comprises the plurality of equivalent network identifiers of the second communication network. Moreover, the exemplary method also includes the operations of blocks 550 and 560, where the NFc sends to an NFp of a first communication network, a service request for a service provided by the NFp, wherein the service request comprises the access token with the access token claim comprising the plurality of equivalent network identifiers of the second communication network, and receives, from the NFp, a response upon successful verification of the second communication network at least partly based on at least one of: the access token, at least one additional identifier of the plurality of equivalent network identifiers of the second communication network.In some embodiments, the first communication network and the second communication network are different communication networks.In an embodiment, the access token request is a request for an access token for a service provided by the NFp.In some embodiments, the at least one additional identifier of the plurality of equivalent network identifiers of the second communication network is a header of the service request comprising the plurality of equivalent network identifiers of the second communication network.In some embodiments, the header of the service request is a 3gpp-Sbi-Originating-Network-Id header.In some embodiments, the exemplary method further comprises the operations of block 530, where the NFc generates the header to be attached to the service request, the header comprising the plurality of equivalent network identifiers of the second communication network, prior to sending the service request, wherein the service request sent to the NFp further comprises the generated header.In some embodiments, the first and the second communication networks are fifth-generation (5G) mobile networks. In embodiments the first communication network and / or the second communication network is a PLMN. In embodiments the first communication network and / or the second communication network is a SNPN.In addition, Fig. 6 illustrates an exemplary method (e.g., procedure) for a network node of a second communication network (e.g., 5GC), the communication network having a plurality of equivalent network identifiers, according to various embodiments of the present disclosure.The exemplary method includes the operations of block 610, where the network node receives, from an NFc in the second communication network, a service request for a service provided by an NFp, wherein the service request comprises an access token with an access token claim comprising the plurality of equivalent network identifiers of the second communication network. The exemplary method also includes the operations of blocks 620 and 630, where the network node generates a header to be attached to the service request, the header comprisingthe plurality of equivalent network identifiers of the second communication network, if the service request has no header comprising the plurality of equivalent network identifiers of the second communication network, and sends the service request with the generated header to the NFp.In some embodiments, the network node is an SCP or a SEPP. Thus, the exemplary method shown in Fig. 6 can be performed by an SCP or a SEPP or network equipment configured to implement an SCP or a SEPP, such as described elsewhere herein.In some embodiments, the second communication network is a PLMN. In embodiments, the second communication network is a SNPN. In embodiments, the NFc and the NFp are located in different communication networks.In some embodiments, when the service request received from the NFc comprises the header comprising the plurality of equivalent network identifiers of the second communication network, the exemplary method further includes the operations of blocks 640 or 650 where the SEPP sends, towards the NFp, the service request together with the header comprising the plurality of equivalent network identifiers of the second communication network towards, if any one of the equivalent network identifiers of the second communication network in the header correspond to any of the plurality of equivalent network identifiers of the SEPP communication network, or discards the service request if any one of the equivalent network identifiers of the communication network in the header does not correspond to any of network identifiers of the SEPP communication network.In addition, Fig. 7 illustrates an exemplary method (e.g., procedure) for a SEPP of a first communication network (e.g., 5GC), according to various embodiments of the present disclosure.The exemplary method includes the operations of block 710, where the SEPP receives, via a SEPP of a second communication network, the second communication network having a plurality of equivalent network identifiers, a service request from an NFc for a service provided by an NFp, the service request comprising a plurality of equivalent network identifiers of the second communication network. The exemplary method also includes the operations of blocks 720-740, where the SEPP obtains at least one additional identifier of the second communicationnetwork, verifies the second communication network at least partly based on the information related to the plurality of equivalent network identifiers of the second communication network and the at least one additional identifier of the second communication network, and sends, to the NFp, the service request upon successful verification of the second communication network.In embodiments, he plurality of equivalent network identifiers of the second communication network in the service request is provided in at least one of: an access token claim of an access token for the service provided by the NFp, a header of the service request.In embodiments, the header of the service request is a 3gpp-Sbi-Originating-Network-Id header.In embodiments, the at least one additional identifier of the second communication network comprises at least one of: a network identifier of the second communication network according to aN32-f context, a network identifier of the second communication network according to a certificate of the SEPP of a second communication network, a network identifier of the second communication network according to a locally configured list of network identifiers.In embodiments, the second communication network is successfully verified when at least one of the equivalent network identifiers of the second communication network corresponds to the at least one additional identifier of the second communication network.In embodiments, the first and / or the second communication network is a PLMN. In embodiments, the first and / or the second communication network is a SNPN.In addition, Fig. 8 illustrates an exemplary method (e.g., procedure) for an NFp of a first communication network (e.g., 5GC), according to various embodiments of the present disclosure.The exemplary method includes the operations of block 810, where the NFp receives, from a NFc of a second communication network, the second communication network having a plurality of equivalent network identifiers, a service request for a service provided by a NFp of the first communication network, wherein the service request comprises a network identifier of the second communication network and at least one additional network identifier comprising the plurality of equivalent network identifiers. The exemplary method also includes the operations of blocks 820 and 830, where the network node verifies the second communication network at least partly based on the network identifier of the second communication network in the service request and the at least one additional network identifier comprising the plurality of equivalent network identifiers, and sends, to the NFc a response to the service request at least partly based on the verification of the second communication network.In embodiments, the plurality of equivalent network identifiers of the second communication network in the service request is provided in at least one of: an access token claim of an access token for the service provided by the NFp, a header of the service request.In embodiments, the header of the service request is a 3gpp-Sbi-Originating-Network-Id header.In embodiments, the second communication network is successfully verified when the network identifier of the second communication network in the service request is equal to at least one equivalent network identifier from the plurality of equivalent network identifiers of the second communication network in the access token claim of the access token for the service provided by the NFp, and / or the network identifier of the second communication network in the service request is equal to at least one equivalent network identifier from the plurality of equivalent network identifiers of the second communication network in the header of the service request.In embodiments, the first and / or the second communication network is a PLMN. In embodiments, the first and / or the second communication network is a SNPN.Figure 9 shows an example of a communication system 1100 in accordance with some embodiments.In the example, the communication system 1100 includes a telecommunication network 1102 that includes an access network 1104, such as a radio access network (RAN), and a core network 1106, which includes one or more core network nodes 1108. The access network 1104 includes one or more access network nodes, such as network nodes 1110a and 1110b (one or more of which may be generally referred to as network nodes 1110), or any other similar 3rdGeneration Partnership Project (3GPP) access nodes or non-3GPP access points. Moreover, as will be appreciated by those of skill in the art, a network node is not necessarily limited to an implementation in which a radio portion and a baseband portion are supplied and integrated by a single vendor. Thus, it will be understood that network nodes include disaggregated implementations or portions thereof. For example, in some embodiments, the telecommunication network 1102 includes one or more Open-RAN (ORAN) network nodes. An ORAN network node is a node in the telecommunication network 1102 that supports an ORAN specification (e.g., a specification published by the O-RAN Alliance, or any similar organization) and may operate alone or together with other nodes to implement one or more functionalities of any node in the telecommunication network 1102, including one or more network nodes 1110 and / or core network nodes 1108.Examples of an ORAN network node include an open radio unit (O-RU), an open distributed unit (O-DU), an open central unit (O-CU), including an O-CU control plane (O-CU-CP) or an O-CU user plane (O-CU-UP), a RAN intelligent controller (near-real time or non-real time) hosting software or software plug-ins, such as a near-real time control application (e.g., xApp) or a non-real time control application (e.g., rApp), or any combination thereof (the adjective “open” designating support of an ORAN specification). The network node may support a specification by, for example, supporting an interface defined by the ORAN specification, such as an Al, Fl, Wl, El, E2, X2, Xn interface, an open fronthaul user plane interface, or an open fronthaul management plane interface. Moreover, an ORAN access node may be a logical node in a physical node. Furthermore, an ORAN network node may be implemented in a virtualization environment (described further below) in which one or more network functions are virtualized. For example, the virtualization environment may include an O-Cloud computing platform orchestrated by a Service Management and Orchestration Framework via an O-2 interface defined by the O-RAN Alliance or comparable technologies. The network nodes 1110 facilitate direct or indirect connection of user equipment (UE), such as byconnecting UEs 1112a, 1112b, 1112c, and 1112d (one or more of which may be generally referred to as UEs 1112) to the core network 1106 over one or more wireless connections.Example wireless communications over a wireless connection include transmitting and / or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and / or other types of signals suitable for conveying information without the use of wires, cables, or other material conductors. Moreover, in different embodiments, the communication system 1100 may include any number of wired or wireless networks, network nodes, UEs, and / or any other components or systems that may facilitate or participate in the communication of data and / or signals whether via wired or wireless connections. The communication system 1100 may include and / or interface with any type of communication, telecommunication, data, cellular, radio network, and / or other similar type of system.The UEs 1112 may be any of a wide variety of communication devices, including wireless devices arranged, configured, and / or operable to communicate wirelessly with the network nodes 1110 and other communication devices. Similarly, the network nodes 1110 are arranged, capable, configured, and / or operable to communicate directly or indirectly with the UEs 1112 and / or with other network nodes or equipment in the telecommunication network 1102 to enable and / or provide network access, such as wireless network access, and / or to perform other functions, such as administration in the telecommunication network 1102.In the depicted example, the core network 1106 connects the network nodes 1110 to one or more host computing systems, such as host 1116. These connections may be direct or indirect via one or more intermediary networks or devices. In other examples, network nodes may be directly coupled to hosts. The core network 1106 includes one more core network nodes (e.g., core network node 1108) that are structured with hardware and software components. Features of these components may be substantially similar to those described with respect to the UEs, network nodes, and / or hosts, such that the descriptions thereof are generally applicable to the corresponding components of the core network node 1108. Example core network nodes include functions of one or more of a Mobile Switching Center (MSC), Mobility Management Entity (MME), Home Subscriber Server (HSS), Access and Mobility Management Function (AMF), Session Management Function (SMF), Authentication Server Function (AUSF), Subscription Identifier De-concealing function (SIDF), Unified Data Management (UDM), Security Edge Protection Proxy (SEPP), Network Exposure Function (NEF), and / or a User Plane Function (UPF).The host 1116 may be under the ownership or control of a service provider other than an operator or provider of the access network 1104 and / or the telecommunication network 1102. The host 1116 may host a variety of applications to provide one or more service. Examples of such applications include live and pre-recorded audio / video content, data collection services such as retrieving and compiling data on various ambient conditions detected by a plurality of UEs, analytics functionality, social media, functions for controlling or otherwise interacting with remote devices, functions for an alarm and surveillance center, or any other such function performed by a server.As a whole, the communication system 1100 of Fig. 11 enables connectivity between the UEs, network nodes, and hosts. In that sense, the communication system may be configured to operate according to predefined rules or procedures, such as specific standards that include, but are not limited to: Global System for Mobile Communications (GSM); Universal Mobile Telecommunications System (UMTS); Long Term Evolution (LTE), and / or other suitable 2G, 3G, 4G, 5G standards, or any applicable future generation standard (e.g., 6G); wireless local area network (WLAN) standards, such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards (WiFi); and / or any other appropriate wireless communication standard, such as the Worldwide Interoperability for Microwave Access (WiMax), Bluetooth, Z-Wave, Near Field Communication (NFC) ZigBee, LiFi, and / or any low-power wide-area network (LPWAN) standards such as LoRa and Sigfox.In some examples, the telecommunication network 1102 is a cellular network that implements 3GPP standardized features. Accordingly, the telecommunications network 1102 may support network slicing to provide different logical networks to different devices that are connected to the telecommunication network 1102. For example, the telecommunications network 1102 may provide Ultra Reliable Low Latency Communication (URLLC) services to some UEs, while providing Enhanced Mobile Broadband (eMBB) services to other UEs, and / or Massive Machine Type Communication (mMTC)ZMassive loT services to yet further UEs.In some examples, the UEs 1112 are configured to transmit and / or receive information without direct human interaction. For instance, a UE may be designed to transmit information to the access network 1104 on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the access network 1104. Additionally, a UE may be configured for operating in single- or multi-RAT or multi-standard mode. For example, a UE may operate with any one or combination of Wi-Fi, NR (New Radio) and LTE, i.e. beingconfigured for multi-radio dual connectivity (MR-DC), such as E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network) New Radio - Dual Connectivity (EN-DC).In the example, the hub 1114 communicates with the access network 1104 to facilitate indirect communication between one or more UEs (e.g., UE 1112c and / or 1112d) and network nodes (e.g., network node 1110b). In some examples, the hub 1114 may be a controller, router, content source and analytics, or any of the other communication devices described herein regarding UEs. For example, the hub 1114 may be a broadband router enabling access to the core network 1106 for the UEs. As another example, the hub 1114 may be a controller that sends commands or instructions to one or more actuators in the UEs. Commands or instructions may be received from the UEs, network nodes 1110, or by executable code, script, process, or other instructions in the hub 1114. As another example, the hub 1114 may be a data collector that acts as temporary storage for UE data and, in some embodiments, may perform analysis or other processing of the data. As another example, the hub 1114 may be a content source. For example, for a UE that is a VR device, display, loudspeaker, or other media delivery device, the hub 1114 may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which the hub 1114 then provides to the UE either directly, after performing local processing, and / or after adding additional local content. In still another example, the hub 1114 acts as a proxy server or orchestrator for the UEs, in particular if one or more of the UEs are low energy loT devices.The hub 1114 may have a constant / persi stent or intermittent connection to the network node 1110b. The hub 1114 may also allow for a different communication scheme and / or schedule between the hub 1114 and UEs (e.g., UE 1112c and / or 1112d), and between the hub 1114 and the core network 1106. In other examples, the hub 1114 is connected to the core network 1106 and / or one or more UEs via a wired connection. Moreover, the hub 1114 may be configured to connect to an M2M service provider over the access network 1104 and / or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with the network nodes 1110 while still connected via the hub 1114 via a wired or wireless connection. In some embodiments, the hub 1114 may be a dedicated hub - that is, a hub whose primary function is to route communications to / from the UEs from / to the network node 1110b. In other embodiments, the hub 1114 may be a non-dedicated hub - that is, a device which is capable of operating to route communications between the UEs and network node 1110b, but which is additionally capable of operating as a communication start and / or end point for certain data channels.Figure 10 shows a UE 1200 in accordance with some embodiments. The UE 1200 presents additional details of some embodiments of the UE 1112 of Fig. 11. As used herein, a UE refers to a device capable, configured, arranged and / or operable to communicate wirelessly with network nodes and / or other UEs. Examples of a UE include, but are not limited to, a smart phone, mobile phone, cell phone, voice over IP (VoIP) phone, wireless local loop phone, desktop computer, personal digital assistant (PDA), wireless cameras, gaming console or device, music storage / playback device, wearable terminal device, wireless endpoint, mobile station, tablet, laptop, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), an Augmented Reality (AR) or Virtual Reality (VR) device, wireless customer-premise equipment (CPE), vehicle, vehicle-mounted or vehicle embedded / integrated wireless device, etc. Other examples include any UE identified by the 3rd Generation Partnership Project (3 GPP), including a narrow band internet of things (NB-IoT) UE, a machine type communication (MTC) UE, and / or an enhanced MTC (eMTC) UE.A UE may support device-to-device (D2D) communication, for example by implementing a 3GPP standard for sidelink communication, Dedicated Short-Range Communication (DSRC), vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), or vehicle-to-everything (V2X). In other examples, a UE may not necessarily have a user in the sense of a human user who owns and / or operates the relevant device. Instead, a UE may represent a device that is intended for sale to, or operation by, a human user but which may not, or which may not initially, be associated with a specific human user (e.g., a smart sprinkler controller). Alternatively, a UE may represent a device that is not intended for sale to, or operation by, an end user but which may be associated with or operated for the benefit of a user (e.g., a smart power meter).The UE 1200 includes processing circuitry 1202 that is operatively coupled via a bus 1204 to an input / output interface 1206, a power source 1208, a memory 1210, a communication interface 1212, and / or any other component, or any combination thereof. Certain UEs may utilize all or a subset of the components shown in Fig. 12. The level of integration between the components may vary from one UE to another UE. Further, certain UEs may contain multiple instances of a component, such as multiple processors, memories, transceivers, transmitters, receivers, etc.The processing circuitry 1202 is configured to process instructions and data and may be configured to implement any sequential state machine operative to execute instructions stored as machine-readable computer programs in the memory 1210. The processing circuitry 1202 may be implemented as one or more hardware-implemented state machines (e.g., in discretelogic, field-programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), etc.); programmable logic together with appropriate firmware; one or more stored computer programs, general-purpose processors, such as a microprocessor or digital signal processor (DSP), together with appropriate software; or any combination of the above. For example, the processing circuitry 1202 may include multiple central processing units (CPUs). In the example, the input / output interface 1206 may be configured to provide an interface or interfaces to an input device, output device, or one or more input and / or output devices. Examples of an output device include a speaker, a sound card, a video card, a display, a monitor, a printer, an actuator, an emitter, a smartcard, another output device, or any combination thereof. An input device may allow a user to capture information into the UE 1200. Examples of an input device include a touch-sensitive or presence-sensitive display, a camera (e.g., a digital camera, a digital video camera, a web camera, etc.), a microphone, a sensor, a mouse, a trackball, a directional pad, a trackpad, a scroll wheel, a smartcard, and the like. The presence-sensitive display may include a capacitive or resistive touch sensor to sense input from a user. A sensor may be, for instance, an accelerometer, a gyroscope, a tilt sensor, a force sensor, a magnetometer, an optical sensor, a proximity sensor, a biometric sensor, etc., or any combination thereof. An output device may use the same type of interface port as an input device. For example, a Universal Serial Bus (USB) port may be used to provide an input device and an output device.In some embodiments, the power source 1208 is structured as a battery or battery pack. Other types of power sources, such as an external power source (e.g., an electricity outlet), photovoltaic device, or power cell, may be used. The power source 1208 may further include power circuitry for delivering power from the power source 1208 itself, and / or an external power source, to the various parts of the UE 1200 via input circuitry or an interface such as an electrical power cable. Delivering power may be, for example, for charging of the power source 1208. Power circuitry may perform any formatting, converting, or other modification to the power from the power source 1208 to make the power suitable for the respective components of the UE 1200 to which power is supplied.The memory 1210 may be or be configured to include memory such as random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), magnetic disks, optical disks, hard disks, removable cartridges, flash drives, and so forth. In one example, the memory 1210 includes one or more applicationprograms 1214, such as an operating system, web browser application, a widget, gadget engine, or other application, and corresponding data 1216. The memory 1210 may store, for use by the UE 1200, any of a variety of various operating systems or combinations of operating systems. The memory 1210 may be configured to include a number of physical drive units, such as redundant array of independent disks (RAID), flash memory, USB flash drive, external hard disk drive, thumb drive, pen drive, key drive, high-density digital versatile disc (HD-DVD) optical disc drive, internal hard disk drive, Blu-Ray optical disc drive, holographic digital data storage (HDDS) optical disc drive, external mini-dual in-line memory module (DIMM), synchronous dynamic random access memory (SDRAM), external micro-DIMM SDRAM, smartcard memory such as tamper resistant module in the form of a universal integrated circuit card (UICC) including one or more subscriber identity modules (SIMs), such as a USIM and / or ISIM, other memory, or any combination thereof. The UICC may for example be an embedded UICC (eUICC), integrated UICC (iUICC) or a removable UICC commonly known as ‘SIM card.’ The memory 1210 may allow the UE 1200 to access instructions, application programs and the like, stored on transitory or non-transitory memory media, to off-load data, or to upload data. An article of manufacture, such as one utilizing a communication system may be tangibly embodied as or in the memory 1210, which may be or comprise a device-readable storage medium.The processing circuitry 1202 may be configured to communicate with an access network or other network using the communication interface 1212. The communication interface 1212 may comprise one or more communication subsystems and may include or be communicatively coupled to an antenna 1222. The communication interface 1212 may include one or more transceivers used to communicate, such as by communicating with one or more remote transceivers of another device capable of wireless communication (e.g., another UE or a network node in an access network). Each transceiver may include a transmitter 1218 and / or a receiver 1220 appropriate to provide network communications (e.g., optical, electrical, frequency allocations, and so forth). Moreover, the transmitter 1218 and receiver 1220 may be coupled to one or more antennas (e.g., antenna 1222) and may share circuit components, software or firmware, or alternatively be implemented separately.In the illustrated embodiment, communication functions of the communication interface 1212 may include cellular communication, Wi-Fi communication, LPWAN communication, data communication, voice communication, multimedia communication, short-range communications such as Bluetooth, near-field communication, location-based communicationsuch as the use of the global positioning system (GPS) to determine a location, another like communication function, or any combination thereof. Communications may be implemented in according to one or more communication protocols and / or standards, such as IEEE 802.11, Code Division Multiplexing Access (CDMA), Wideband Code Division Multiple Access (WCDMA), GSM, LTE, New Radio (NR), UMTS, WiMax, Ethernet, transmission control protocol / intemet protocol (TCP / IP), synchronous optical networking (SONET), Asynchronous Transfer Mode (ATM), QUIC, Hypertext Transfer Protocol (HTTP), and so forth.Regardless of the type of sensor, a UE may provide an output of data captured by its sensors, through its communication interface 1212, via a wireless connection to a network node. Data captured by sensors of a UE can be communicated through a wireless connection to a network node via another UE. The output may be periodic (e.g., once every 15 minutes if it reports the sensed temperature), random (e.g., to even out the load from reporting from several sensors), in response to a triggering event (e.g., when moisture is detected an alert is sent), in response to a request (e.g., a user initiated request), or a continuous stream (e.g., a live video feed of a patient).As another example, a UE comprises an actuator, a motor, or a switch, related to a communication interface configured to receive wireless input from a network node via a wireless connection. In response to the received wireless input the states of the actuator, the motor, or the switch may change. For example, the UE may comprise a motor that adjusts the control surfaces or rotors of a drone in flight according to the received input or to a robotic arm performing a medical procedure according to the received input.A UE, when in the form of an Internet of Things (loT) device, may be a device for use in one or more application domains, these domains comprising, but not limited to, city wearable technology, extended industrial application and healthcare. Non-limiting examples of such an loT device are a device which is or which is embedded in: a connected refrigerator or freezer, a TV, a connected lighting device, an electricity meter, a robot vacuum cleaner, a voice controlled smart speaker, a home security camera, a motion detector, a thermostat, a smoke detector, a door / window sensor, a flood / moisture sensor, an electrical door lock, a connected doorbell, an air conditioning system like a heat pump, an autonomous vehicle, a surveillance system, a weather monitoring device, a vehicle parking monitoring device, an electric vehicle charging station, a smart watch, a fitness tracker, a wearable for tactile augmentation or sensory enhancement, a water sprinkler, an animal- or item-tracking device, a sensor for monitoring a plant or animal, an industrial robot, an Unmanned Aerial Vehicle (UAV), and any kind ofmedical device, like a heart rate monitor or a remote controlled surgical robot. A UE in the form of an loT device comprises circuitry and / or software in dependence of the intended application of the loT device in addition to other components as described in relation to the UE 1200 shown in Fig. 12.As yet another specific example, in an loT scenario, a UE may represent a machine or other device that performs monitoring and / or measurements, and transmits the results of such monitoring and / or measurements to another UE and / or a network node. The UE may in this case be an M2M device, which may in a 3GPP context be referred to as an MTC device. As one particular example, the UE may implement the 3GPP NB-IoT standard. In other scenarios, a UE may represent a vehicle, such as a car, a bus, a truck, a ship and an airplane, or other equipment that is capable of monitoring and / or reporting on its operational status or other functions associated with its operation.In practice, any number of UEs may be used together with respect to a single use case. For example, a first UE might be or be integrated in a drone and provide the drone’s speed information (obtained through a speed sensor) to a second UE that is a remote controller operating the drone. When the user makes changes from the remote controller, the first UE may adjust the throttle on the drone (e.g. by controlling an actuator) to increase or decrease the drone’s speed. The first and / or the second UE can also include more than one of the functionalities described above. For example, a UE might comprise the sensor and the actuator, and handle communication of data for both the speed sensor and the actuators.Figure 11 shows a network node 1300 in accordance with some embodiments. As used herein, network node refers to equipment capable, configured, arranged and / or operable to communicate directly or indirectly with a UE and / or with other network nodes or equipment, in a telecommunication network. Examples of network nodes include, but are not limited to, access points (APs) (e.g., radio access points), base stations (BSs) (e.g., radio base stations, Node Bs, evolved Node Bs (eNBs) and NRNodeBs (gNBs)), O-RAN nodes or components of an O-RAN node (e.g., O-RU, O-DU, O-CU).Base stations may be categorized based on the amount of coverage they provide (or, stated differently, their transmit power level) and so, depending on the provided amount of coverage, may be referred to as femto base stations, pico base stations, micro base stations, or macro base stations. A base station may be a relay node or a relay donor node controlling a relay. A network node may also include one or more (or all) parts of a distributed radio base station such as centralized digital units, distributed units (e.g., in an O-RAN access node) and / or remote radiounits (RRUs), sometimes referred to as Remote Radio Heads (RRHs). Such remote radio units may or may not be integrated with an antenna as an antenna integrated radio. Parts of a distributed radio base station may also be referred to as nodes in a distributed antenna system (DAS).Other examples of network nodes include multiple transmission point (multi-TRP) 5G access nodes, multi-standard radio (MSR) equipment such as MSR BSs, network controllers such as radio network controllers (RNCs) or base station controllers (BSCs), base transceiver stations (BTSs), transmission points, transmission nodes, multi-cell / multicast coordination entities (MCEs), Operation and Maintenance (O&M) nodes, Operations Support System (OSS) nodes, Self-Organizing Network (SON) nodes, positioning nodes (e.g., Evolved Serving Mobile Location Centers (E-SMLCs)), and / or Minimization of Drive Tests (MDTs).The network node 1300 includes a processing circuitry 1302, amemory 1304, a communication interface 1306, and a power source 1308. The network node 1300 may be composed of multiple physically separate components (e.g., a NodeB component and a RNC component, or a BTS component and a BSC component, etc.), which may each have their own respective components. In certain scenarios in which the network node 1300 comprises multiple separate components (e.g., BTS and BSC components), one or more of the separate components may be shared among several network nodes. For example, a single RNC may control multiple NodeBs. In such a scenario, each unique NodeB and RNC pair, may in some instances be considered a single separate network node. In some embodiments, the network node 1300 may be configured to support multiple radio access technologies (RATs). In such embodiments, some components may be duplicated (e.g., separate memory 1304 for different RATs) and some components may be reused (e.g., a same antenna 1310 may be shared by different RATs). The network node 1300 may also include multiple sets of the various illustrated components for different wireless technologies integrated into network node 1300, for example GSM, WCDMA, LTE, NR, WiFi, Zigbee, Z-wave, LoRaWAN, Radio Frequency Identification (RFID) or Bluetooth wireless technologies. These wireless technologies may be integrated into the same or different chip or set of chips and other components within network node 1300.The processing circuitry 1302 may comprise a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, applicationspecific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, software and / or encoded logic operable toprovide, either alone or in conjunction with other network node 1300 components, such as the memory 1304, to provide network node 1300 functionality.In some embodiments, the processing circuitry 1302 includes a system on a chip (SOC). In some embodiments, the processing circuitry 1302 includes one or more of radio frequency (RF) transceiver circuitry 1312 and baseband processing circuitry 1314. In some embodiments, the radio frequency (RF) transceiver circuitry 1312 and the baseband processing circuitry 1314 may be on separate chips (or sets of chips), boards, or units, such as radio units and digital units. In alternative embodiments, part or all of RF transceiver circuitry 1312 and baseband processing circuitry 1314 may be on the same chip or set of chips, boards, or units.The memory 1304 may comprise any form of volatile or non-volatile computer-readable memory including, without limitation, persistent storage, solid-state memory, remotely mounted memory, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), mass storage media (for example, a hard disk), removable storage media (for example, a flash drive, a Compact Disk (CD) or a Digital Video Disk (DVD)), and / or any other volatile or non-volatile, non-transitory device-readable and / or computer-executable memory devices that store information, data, and / or instructions that may be used by the processing circuitry 1302. The memory 1304 may store any suitable instructions, data, or information, including a computer program, software, an application including one or more of logic, rules, code, tables, and / or other instructions capable of being executed by the processing circuitry 1302 and utilized by the network node 1300. The memory 1304 may be used to store any calculations made by the processing circuitry 1302 and / or any data received via the communication interface 1306. In some embodiments, the processing circuitry 1302 and memory 1304 is integrated.The communication interface 1306 is used in wired or wireless communication of signaling and / or data between a network node, access network, and / or UE. As illustrated, the communication interface 1306 comprises port(s) / terminal(s) 1316 to send and receive data, for example to and from a network over a wired connection. The communication interface 1306 also includes radio front-end circuitry 1318 that may be coupled to, or in certain embodiments a part of, the antenna 1310. Radio front-end circuitry 1318 comprises filters 1320 and amplifiers 1322. The radio front-end circuitry 1318 may be connected to an antenna 1310 and processing circuitry 1302. The radio front-end circuitry may be configured to condition signals communicated between antenna 1310 and processing circuitry 1302. The radio front-end circuitry 1318 may receive digital data that is to be sent out to other network nodes or UEs viaa wireless connection. The radio front-end circuitry 1318 may convert the digital data into a radio signal having the appropriate channel and bandwidth parameters using a combination of filters 1320 and / or amplifiers 1322. The radio signal may then be transmitted via the antenna 1310. Similarly, when receiving data, the antenna 1310 may collect radio signals which are then converted into digital data by the radio front-end circuitry 1318. The digital data may be passed to the processing circuitry 1302. In other embodiments, the communication interface may comprise different components and / or different combinations of components.In certain alternative embodiments, the network node 1300 does not include separate radio front-end circuitry 1318, instead, the processing circuitry 1302 includes radio front-end circuitry and is connected to the antenna 1310. Similarly, in some embodiments, all or some of the RF transceiver circuitry 1312 is part of the communication interface 1306. In still other embodiments, the communication interface 1306 includes one or more ports or terminals 1316, the radio front-end circuitry 1318, and the RF transceiver circuitry 1312, as part of a radio unit (not shown), and the communication interface 1306 communicates with the baseband processing circuitry 1314, which is part of a digital unit (not shown).The antenna 1310 may include one or more antennas, or antenna arrays, configured to send and / or receive wireless signals. The antenna 1310 may be coupled to the radio front-end circuitry 1318 and may be any type of antenna capable of transmitting and receiving data and / or signals wirelessly. In certain embodiments, the antenna 1310 is separate from the network node 1300 and connectable to the network node 1300 through an interface or port.The antenna 1310, communication interface 1306, and / or the processing circuitry 1302 may be configured to perform any receiving operations and / or certain obtaining operations described herein as being performed by the network node. Any information, data and / or signals may be received from a UE, another network node and / or any other network equipment. Similarly, the antenna 1310, the communication interface 1306, and / or the processing circuitry 1302 may be configured to perform any transmitting operations described herein as being performed by the network node. Any information, data and / or signals may be transmitted to a UE, another network node and / or any other network equipment.The power source 1308 provides power to the various components of network node 1300 in a form suitable for the respective components (e.g., at a voltage and current level needed for each respective component). The power source 1308 may further comprise, or be coupled to, power management circuitry to supply the components of the network node 1300 with power for performing the functionality described herein. For example, the network node 1300 may beconnectable to an external power source (e.g., the power grid, an electricity outlet) via an input circuitry or interface such as an electrical cable, whereby the external power source supplies power to power circuitry of the power source 1308. As a further example, the power source 1308 may comprise a source of power in the form of a battery or battery pack which is connected to, or integrated in, power circuitry. The battery may provide backup power should the external power source fail.Embodiments of the network node 1300 may include additional components beyond those shown in Fig. 13 for providing certain aspects of the network node’s functionality, including any of the functionality described herein and / or any functionality necessary to support the subject matter described herein. For example, the network node 1300 may include user interface equipment to allow input of information into the network node 1300 and to allow output of information from the network node 1300. This may allow a user to perform diagnostic, maintenance, repair, and other administrative functions for the network node 1300. In some embodiments providing a core network node, such as core network node 108 of FIG. 11, some components, such as the radio front-end circuitry 1318 and the RF transceiver circuitry 1312 may be omitted.Figure 12 is a block diagram illustrating a virtualization environment 1400 in which functions implemented by some embodiments may be virtualized. In the present context, virtualizing means creating virtual versions of apparatuses or devices which may include virtualizing hardware platforms, storage devices and networking resources. As used herein, virtualization can be applied to any device described herein, or components thereof, and relates to an implementation in which at least a portion of the functionality is implemented as one or more virtual components. Some or all of the functions described herein may be implemented as virtual components executed by one or more virtual machines (VMs) implemented in one or more virtual environments 1400 hosted by one or more of hardware nodes, such as a hardware computing device that operates as a network node, UE, core network node, or host. Further, in embodiments in which the virtual node does not require radio connectivity (e.g., a core network node or host), then the node may be entirely virtualized. In some embodiments, the virtualization environment 1400 includes components defined by the O-RAN Alliance, such as an O-Cloud environment orchestrated by a Service Management and Orchestration Framework via an O-2 interface. Virtualization may facilitate distributed implementations of a network node, UE, core network node, or host.Applications 1402 (which may alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc.) are run in the virtualization environment Q400 to implement some of the features, functions, and / or benefits of some of the embodiments disclosed herein.Hardware 1404 includes processing circuitry, memory that stores software and / or instructions executable by hardware processing circuitry, and / or other hardware devices as described herein, such as a network interface, input / output interface, and so forth. Software may be executed by the processing circuitry to instantiate one or more virtualization layers 1406 (also referred to as hypervisors or virtual machine monitors (VMMs)), provide VMs 1408a and 1408b (one or more of which may be generally referred to as VMs 1408), and / or perform any of the functions, features and / or benefits described in relation with some embodiments described herein. The virtualization layer 1406 may present a virtual operating platform that appears like networking hardware to the VMs 1408.The VMs 1408 comprise virtual processing, virtual memory, virtual networking or interface and virtual storage, and may be run by a corresponding virtualization layer 1406. Different embodiments of the instance of a virtual appliance 1402 may be implemented on one or more of VMs 1408, and the implementations may be made in different ways. Virtualization of the hardware is in some contexts referred to as network function virtualization (NFV). NFV may be used to consolidate many network equipment types onto industry standard high volume server hardware, physical switches, and physical storage, which can be located in data centers, and customer premise equipment.In the context of NFV, a VM 1408 may be a software implementation of a physical machine that runs programs as if they were executing on a physical, non-virtualized machine. Each of the VMs 1408, and that part of hardware 1404 that executes that VM, be it hardware dedicated to that VM and / or hardware shared by that VM with others of the VMs, forms separate virtual network elements. Still in the context of NFV, a virtual network function is responsible for handling specific network functions that run in one or more VMs 1408 on top of the hardware 1404 and corresponds to the application 1402.Hardware 1404 may be implemented in a standalone network node with generic or specific components. Hardware 1404 may implement some functions via virtualization. Alternatively, hardware 1404 may be part of a larger cluster of hardware (e.g. such as in a data center or CPE) where many hardware nodes work together and are managed via management and orchestration 1410, which, among others, oversees lifecycle management of applications 1402. In someembodiments, hardware 1404 is coupled to one or more radio units that each include one or more transmitters and one or more receivers that may be coupled to one or more antennas. Radio units may communicate directly with other hardware nodes via one or more appropriate network interfaces and may be used in combination with the virtual components to provide a virtual node with radio capabilities, such as a radio access node or a base station. In some embodiments, some signaling can be provided with the use of a control system 1412 which may alternatively be used for communication between hardware nodes and radio units.Although the computing devices described herein (e.g., UEs, network nodes) may include the illustrated combination of hardware components, other embodiments may comprise computing devices with different combinations of components. It is to be understood that these computing devices may comprise any suitable combination of hardware and / or software needed to perform the tasks, features, functions and methods disclosed herein. Determining, calculating, obtaining or similar operations described herein may be performed by processing circuitry, which may process information by, for example, converting the obtained information into other information, comparing the obtained information or converted information to information stored in the network node, and / or performing one or more operations based on the obtained information or converted information, and as a result of said processing making a determination. Moreover, while components are depicted as single boxes located within a larger box, or nested within multiple boxes, in practice, computing devices may comprise multiple different physical components that make up a single illustrated component, and functionality may be partitioned between separate components. For example, a communication interface may be configured to include any of the components described herein, and / or the functionality of the components may be partitioned between the processing circuitry and the communication interface. In another example, non-computationally intensive functions of any of such components may be implemented in software or firmware and computationally intensive functions may be implemented in hardware.In certain embodiments, some or all of the functionality described herein may be provided by processing circuitry executing instructions stored on in memory, which in certain embodiments may be a computer program product in the form of a non-transitory computer-readable storage medium. In alternative embodiments, some or all of the functionality may be provided by the processing circuitry without executing instructions stored on a separate or discrete device- readable storage medium, such as in a hard-wired manner. In any of those particular embodiments, whether executing instructions stored on a non-transitory computer-readablestorage medium or not, the processing circuitry can be configured to perform the described functionality. The benefits provided by such functionality are not limited to the processing circuitry alone or to other components of the computing device, but are enjoyed by the computing device as a whole, and / or by end users and a wireless network generally.EMBODIMENTSGroup A EmbodimentsAl. A method performed by a Network Repository Function (NRF) of a first communication network, the method comprising: receiving (410), from a Network Function service consumer (NFc) of a second communication network having a plurality of equivalent network identifiers, an access token request, the access token request comprising the plurality of equivalent network identifiers, wherein the access token request is a request for an access token for a service provided by a Network Function service producer (NFp) of the first communication network; generating (420) the access token comprising a claim with the plurality of equivalent network identifiers of the second communication network; and sending (430) the access token towards the NFc.A2. The method of embodiment Al wherein the first communication network and the second communication network are different communication networks.A3. The method of any of embodiments A1-A2 wherein the first communication network and / or the second communication network is a Public Land Mobile Network (PLMN).A4. The method of embodiment A1-A2 wherein the first communication network and / or the second communication network is a Standalone Non-Public Network (SNPN).Group B EmbodimentsBl. A method performed by a Network Function service consumer (NFc) of a second communication network, the communication network having a plurality of equivalent network identifiers, the method comprising: sending (510), to a Network Repository Function (NRF), an access token request, wherein the access token request comprises the plurality of equivalent network identifiers of the second communication network; receiving (520) from the NRF an access token, wherein an access token claim comprisesthe plurality of equivalent network identifiers of the second communication network, sending (540), to a Network Function service producer (NFp) of a first communication network, a service request for a service provided by the NFp, wherein the service request comprises the access token with the access token claim comprising the plurality of equivalent network identifiers of the second communication network; and receiving (550), from the NFp, a response upon successful verification of the second communication network at least partly based on at least one of: the access token, at least one additional identifier of the plurality of equivalent network identifiers of the second communication network.B2. The method of embodiment Bl wherein the first communication network and the second communication network are different communication networks.B3. The method of any of embodiments B 1 -B2 wherein the access token request is a request for an access token for a service provided by the Network Function service producer (NFp).B4. The method of any of embodiments B1-B3 wherein the at least one additional identifier of the plurality of equivalent network identifiers of the second communication network is a header of the service request comprising the plurality of equivalent network identifiers of the second communication network.B5. The method of embodiment B4 wherein the header of the service request is a 3gpp- Sbi-Originating-Network-Id header.B6. The method of any of embodiments B4-B5 further comprising generating (530) the header to be attached to the service request, the header comprising the plurality of equivalent network identifiers of the second communication network, prior to sending the service request, wherein the service request sent to the NFp further comprises the generated header.B7. The method of any of embodiments B1-B6 wherein the first communication network and / or the second communication network is a Public Land Mobile Network (PLMN).B8. The method of embodiment B1-B7 wherein the first communication network and / or the second communication network is a Standalone Non-Public Network (SNPN).Group C EmbodimentsCl. A method performed by a network node of a second communication network, the communication network having a plurality of equivalent network identifiers, the method comprising: receiving (610), from a Network Function service consumer (NFc) in the second communication network, a service request for a service provided by a Network Function Service Producer (NFp), wherein the service request comprises an access token with an access token claim comprising the plurality of equivalent network identifiers of the second communication network; generating (620) a header to be attached to the service request, the header comprising the plurality of equivalent network identifiers of the second communication network, if the service request has no header comprising the plurality of equivalent network identifiers of the second communication network; and sending (630) the service request with the generated header to the NFp.C2. The method of embodiment Cl wherein the network node is a Service Communication Proxy (SCP).C3. The method of embodiment Cl wherein the network node is a Security Edge Protection Proxy (SEPP).C4. The method of any of embodiments C1-C3 wherein the second communication network is a Public Land Mobile Network (PLMN).C5. The method of any of embodiments C1-C3 wherein the second communication network is a Standalone Non-Public Network (SNPN).C6. The method of any of embodiments C1-C5 wherein the NFc and the NFp are locatedin different communication networks.C7. The method of any of embodiments C3-C6, further comprising when the service request received from the Network Function service consumer (NFc) comprises the header comprising the plurality of equivalent network identifiers of the second communication network, sending (640), towards the NFp, the service request together with the header comprising the plurality of equivalent network identifiers of the second communication network towards, if any one of the equivalent network identifiers of the second communication network in the header correspond to any of the plurality of equivalent network identifiers of the SEPP communication network; or discarding (650) the service request if any one of the equivalent network identifiers of the communication network in the header does not correspond to any of network identifiers of the SEPP communication network.Group D EmbodimentsDI. A method performed by a Security Edge Protection Proxy (SEPP) of a first communication network the method comprising: receiving (710), via a Security Edge Protection Proxy (SEPP) of a second communication network, the second communication network having a plurality of equivalent network identifiers, a service request from a Network Function service consumer (NFc) for a service provided by a Network Function service producer (NFp), the service request comprising a plurality of equivalent network identifiers of the second communication network; obtaining (720) at least one additional identifier of the second communication network; verifying (730) the second communication network at least partly based on the plurality of equivalent network identifiers of the second communication network in the service request and the at least one additional identifier of the second communication network; and sending (740), to the NFp, the service request upon successful verification of the second communication network.D2. The method of embodiments DI wherein the plurality of equivalent network identifiers of the second communication network in the service request is provided in at least one of:An access token claim of an access token for the service provided by the NFp,a header of the service request.D3. The method of any of embodiments D2 wherein the header of the service request is a 3gpp-Sbi-Originating-Network-Id header.D4. The method of any of embodiments D1-D3 wherein the at least one additional identifier of the second communication network comprises at least one of: a network identifier of the second communication network according to aN32-f context, a network identifier of the second communication network according to a certificate of the SEPP of a second communication network, a network identifier of the second communication network according to a locally configured list of network identifiers.D5. The method of any of embodiments D1-D4, wherein the second communication network is successfully verified when at least one of the equivalent network identifiers of the second communication network corresponds to the at least one additional identifier of the second communication network.D6. The method of any of embodiments DI - D5 wherein the first and / or the second communication network is a Public Land Mobile Network (PLMN).D7. The method of any of embodiments DI - D6 wherein the first and / or the second communication network is a Standalone Non-Public Network (SNPN).Group E EmbodimentsEl. A method performed by a Network Function service producer (NFp) of a first communication network the method comprising: receiving (810), from a Network Function service consumer (NFc) of a second communication network, the second communication network having a plurality of equivalent network identifiers, a service request for a service provided by a NFp of the first communication network, wherein the service request comprises a network identifier of the second communication network and at least one additional network identifier comprising the plurality of equivalent network identifiers;verifying (820) the second communication network at least partly based on the network identifier of the second communication network in the service request and the at least one additional network identifier comprising the plurality of equivalent network identifiers; and sending (830), to the NFc a response to the service request at least partly based on the verification of the second communication network.E2. The method of embodiments El wherein the plurality of equivalent network identifiers of the second communication network in the service request is provided in at least one of: an access token claim of an access token for the service provided by the NFp, a header of the service request.E3. The method of any of embodiments E2 wherein the header of the service request is a 3gpp-Sbi-Originating-Network-Id header.E4. The method of any of embodiments E2-E3, wherein the second communication network is successfully verified when the network identifier of the second communication network in the service request is equal to at least one equivalent network identifier from the plurality of equivalent network identifiers of the second communication network in the access token claim of the access token for the service provided by the NFp, and / or the network identifier of the second communication network in the service request is equal to at least one equivalent network identifier from the plurality of equivalent network identifiers of the second communication network in the header of the service request.E5. The method of any of embodiments El - E4 wherein the first and / or the second communication network is a Public Land Mobile Network (PLMN).E6. The method of any of embodiments El - E5 wherein the first and / or the second communication network is a Standalone Non-Public Network (SNPN).Group F EmbodimentsFl. A Network Repository Function (1108, 1300), NRF, of a communication network (304,1102), the NRF being configured to: receive from aNetwork Function service consumer (1108, 1300), NFc, of a second communication network (302, 1102) having a plurality of equivalent network identifiers, an access token request, the access token request comprising the plurality of equivalent network identifiers, wherein the access token request is a request for an access token for a service provided by a Network Function service producer (1108, 1300), NFp, of the first communication network (304, 1102); generate the access token comprising a claim with the plurality of equivalent network identifiers of the second communication network; and send the access token towards the NFc.F2. The NRF of embodiment Fl, being further configured to perform operations corresponding to any of the methods of embodiments A2-A4.F3. A non-transitory, computer-readable medium (1304) storing computer-executable instructions that, when executed by processing circuitry (1302) associated with aNetwork Repository Function (1108, 1300), NRF of a communication network (304, 1102), configure the NRF to perform operations corresponding to any of the methods of embodiments A1-A4.F4. A computer program product comprising computer-executable instructions that, when executed by processing circuitry (1302) associated with a Network Repository Function (1108, 1300), NRF, of a communication network (304, 1102), configure the NRF to perform operations corresponding to any of the methods of embodiments A1-A4.F5. A Network Function service consumer (1108, 1300), NFc, of a second communication network (302, 1102), the NFc being configured to: send, to a Network Repository Function (1108, 1300), NRF, an access token request, wherein the access token request comprises the plurality of equivalent network identifiers of the second communication network; receive from the NRF an access token, wherein an access token claim comprises the plurality of equivalent network identifiers of the second communication network; send, to aNetwork Function service producer (1108, 1300), NFp, of a first communicationnetwork (304, 1102), a service request for a service provided by the NFp, wherein the service request comprises the access token with the access token claim comprising the plurality of equivalent network identifiers of the second communication network; and receive, from the NFp, a response upon successful verification of the second communication network at least partly based on at least one of: the access token, at least one additional identifier of the plurality of equivalent network identifiers of the second communication network.F6. The NFc of embodiment F5, being further configured to perform operations corresponding to any of the methods of embodiments B2-B8.F7. A non-transitory, computer-readable medium (1304) storing computer-executable instructions that, when executed by processing circuitry (1302) associated with a Network Function service consumer (1108, 1300), NFc of a second communication network (302, 1102), configure the NFc to perform operations corresponding to any of the methods of embodiments B1-B8.F8. A computer program product comprising computer-executable instructions that, when executed by processing circuitry (1302) associated with a Network Repository Function (1108, 1300), NRF, of a communication network (304, 1102), configure the NRF to perform operations corresponding to any of the methods of embodiments B1-B8.F9. A network node (1108, 1300) of a second communication network (302, 1102), the communication network having a plurality of equivalent network identifiers, the network node being configured to: receive from a Network Function service consumer, NFc, in the second communication network, a service request for a service provided by a Network Function Service Producer, NFp, wherein the service request comprises an access token with an access token claim comprising the plurality of equivalent network identifiers of the second communication network; generate a header to be attached to the service request, the header comprising the plurality of equivalent network identifiers of the second communication network, if the servicerequest has no header comprising the plurality of equivalent network identifiers of the second communication network; and send the service request with the generated header to the NFp.F10. The network node of embodiment F9, being further configured to perform operations corresponding to any of the methods of embodiments C2-C7.Fll. A non-transitory, computer-readable medium (1304) storing computer-executable instructions that, when executed by processing circuitry (1302) associated with a network node of a second communication network (302, 1102), configure the network node to perform operations corresponding to any of the methods of embodiments C1-C8.F12. A computer program product comprising computer-executable instructions that, when executed by processing circuitry (1302) associated with a network node (1108, 1300) of a second communication network (302, 1102), configure the network node to perform operations corresponding to any of the methods of embodiments C1-C8.F13. A Security Edge Protection Proxy (1108, 1300), SEPP, of a first communication network (304, 1102), the SEPP being configured to; receive, via a SEPP of a second communication network (302, 1102), the second communication network having a plurality of equivalent network identifiers, a service request from a Network Function service consumer, NFc, for a service provided by a Network Function service producer, NFp, the service request comprising a plurality of equivalent network identifiers of the second communication network; obtain at least one additional identifier of the second communication network; verify the second communication network at least partly based on the plurality of equivalent network identifiers of the second communication network in the service request and the at least one additional identifier of the second communication network; and send to the NFp, the service request upon successful verification of the second communication network.F14. The SEPP of embodiment F13, being further configured to perform operations corresponding to any of the methods of embodiments D2-D7.F15. A non-transitory, computer-readable medium (1304) storing computer-executable instructions that, when executed by processing circuitry (1302) associated with a Security Edge Protection Proxy (1108, 1300), SEPP of a first communication network (304, 1102), configure the SEPP to perform operations corresponding to any of the methods of embodiments D1-D7.Fl 6. A computer program product comprising computer-executable instructions that, when executed by processing circuitry (1302) associated with a Security Edge Protection Proxy (1108, 1300), SEPP, of a first communication network (304, 1102), configure the SEPP to perform operations corresponding to any of the methods of embodiments D1-D7.F17. A Network Function service producer (1108, 1300), NFp, of a first communication network (304, 1102), the NFp being configured to: receive, from a Network Function service consumer (1108, 1300), NFc, of a second communication network(302, 1102), the second communication network having a plurality of equivalent network identifiers, a service request for a service provided by a NFp of the first communication network, wherein the service request comprises a network identifier of the second communication network and at least one additional network identifier comprising the plurality of equivalent network identifiers; verify the second communication network at least partly based on the network identifier of the second communication network in the service request and the at least one additional network identifier comprising the plurality of equivalent network identifiers; and send, to the NFc a response to the service request at least partly based on the verification of the second communication network.F18. The NFp of embodiment F17, being further configured to perform operations corresponding to any of the methods of embodiments E2-E6.Fl 9. A non-transitory, computer-readable medium (1304) storing computer-executable instructions that, when executed by processing circuitry (1302) associated with a Network Function service producer (1108, 1300), NFp, of a first communication network (304, 1102), configure the NFp to perform operations corresponding to any of the methods of embodiments E1-E6..F20. A computer program product comprising computer-executable instructions that, when executed by processing circuitry (1302) associated with a Network Function service producer (1108, 1300), NFp, of a first communication network (304, 1102), configure the NFp to perform operations corresponding to any of the methods of embodiments E1-E6..

Claims

CLAIMS1. A method performed by a Network Repository Function, NRF, of a first communication network, the method comprising: receiving (410), from a Network Function service consumer, NFc, of a second communication network having a plurality of equivalent network identifiers, an access token request, the access token request comprising the plurality of equivalent network identifiers, wherein the access token request is a request for an access token for a service provided by a Network Function service producer, NFp, of the first communication network; generating (420) the access token comprising a claim with the plurality of equivalent network identifiers of the second communication network; and sending (430) the access token towards the NFc.

2. The method of claim 1 wherein the first communication network and the second communication network are different communication networks.

3. The method of any of claims 1-2 wherein the first communication network and / or the second communication network is a Public Land Mobile Network, PLMN.

4. The method of any of claims 1-2 wherein the first communication network and / or the second communication network is a Standalone Non-Public Network, SNPN.

5. A method performed by a Network Function service consumer, NFc, of a second communication network, the communication network having a plurality of equivalent network identifiers, the method comprising: sending (510), to a Network Repository Function, NRF, an access token request, wherein the access token request comprises the plurality of equivalent network identifiers of the second communication network; receiving (520) from the NRF an access token, wherein an access token claim comprises the plurality of equivalent network identifiers of the second communication network, sending (540), to a Network Function service producer, NFp, of a first communication network, a service request for a service provided by the NFp, wherein the service requestcomprises the access token with the access token claim comprising the plurality of equivalent network identifiers of the second communication network; and receiving (550), from the NFp, a response upon successful verification of the second communication network at least partly based on at least one of: the access token, at least one additional identifier of the plurality of equivalent network identifiers of the second communication network.

6. The method of claim 5 wherein the first communication network and the second communication network are different communication networks.

7. The method of any of claims 5-6 wherein the access token request is a request for an access token for a service provided by the Network Function service producer, NFp.

8. The method of any of claims 5-7 wherein the at least one additional identifier of the plurality of equivalent network identifiers of the second communication network is a header of the service request comprising the plurality of equivalent network identifiers of the second communication network.

9. The method of claim 8 wherein the header of the service request is a 3gpp-Sbi- Originating-Network-Id header.

10. The method of any of claims 8-9 further comprising generating (530) the header to be attached to the service request, the header comprising the plurality of equivalent network identifiers of the second communication network, prior to sending the service request, wherein the service request sent to the NFp further comprises the generated header.

11. The method of any of claims 5-10 wherein the first communication network and / or the second communication network is a Public Land Mobile Network, PLMN.

12. The method of claims 5-11 wherein the first communication network and / or the second communication network is a Standalone Non-Public Network, SNPN.

13. A method performed by a network node of a second communication network, the communication network having a plurality of equivalent network identifiers, the method comprising: receiving (610), from a Network Function service consumer, NFc, in the second communication network, a service request for a service provided by a Network Function Service Producer, NFp, wherein the service request comprises an access token with an access token claim comprising the plurality of equivalent network identifiers of the second communication network; generating (620) a header to be attached to the service request, the header comprising the plurality of equivalent network identifiers of the second communication network, if the service request has no header comprising the plurality of equivalent network identifiers of the second communication network; and sending (630) the service request with the generated header to the NFp.

14. The method of claim 13 wherein the network node is a Service Communication Proxy, SCP.

15. The method of claim 13 wherein the network node is a Security Edge Protection Proxy, SEPP.

16. The method of any of claims 13-15 wherein the second communication network is a Public Land Mobile Network, PLMN.

17. The method of any of claims 13-15 wherein the second communication network is a Standalone Non-Public Network, SNPN.

18. The method of any of claims 13-17 wherein the NFc and the NFp are located in different communication networks.

19. The method of any of claims 15-18, further comprising when the service request received from the Network Function service consumer, NFc, comprises the header comprising the plurality of equivalent network identifiers of the second communication network,sending (640), towards the NFp, the service request together with the header comprising the plurality of equivalent network identifiers of the second communication network towards, if any one of the equivalent network identifiers of the second communication network in the header correspond to any of the plurality of equivalent network identifiers of the SEPP communication network; or discarding (650) the service request if any one of the equivalent network identifiers of the communication network in the header does not correspond to any of network identifiers of the SEPP communication network.

20. A method performed by a Security Edge Protection Proxy, SEPP, of a first communication network the method comprising: receiving (710), via a SEPP of a second communication network, the second communication network having a plurality of equivalent network identifiers, a service request from a Network Function service consumer, NFc, for a service provided by a Network Function service producer, NFp, the service request comprising a plurality of equivalent network identifiers of the second communication network; obtaining (720) at least one additional identifier of the second communication network; verifying (730) the second communication network at least partly based on the plurality of equivalent network identifiers of the second communication network in the service request and the at least one additional identifier of the second communication network; and sending (740), to the NFp, the service request upon successful verification of the second communication network.

21. The method of claim 20 wherein the plurality of equivalent network identifiers of the second communication network in the service request is provided in at least one of: an access token claim of an access token for the service provided by the NFp, a header of the service request.

22. The method of claim 21 wherein the header of the service request is a 3gpp-Sbi- Originating-Network-Id header.

23. The method of any of claims 20-22 wherein the at least one additional identifier of the second communication network comprises at least one of:a network identifier of the second communication network according to aN32-f context, a network identifier of the second communication network according to a certificate of the SEPP of a second communication network, a network identifier of the second communication network according to a locally configured list of network identifiers.

24. The method of any of claims 20-23, wherein the second communication network is successfully verified when at least one of the equivalent network identifiers of the second communication network corresponds to the at least one additional identifier of the second communication network.

25. The method of any of claims 20-24 wherein the first and / or the second communication network is a Public Land Mobile Network, PLMN.

26. The method of any of claims 20-25 wherein the first and / or the second communication network is a Standalone Non-Public Network, SNPN.

27. A method performed by a Network Function service producer, NFp, of a first communication network the method comprising: receiving (810), from a Network Function service consumer, NFc, of a second communication network, the second communication network having a plurality of equivalent network identifiers, a service request for a service provided by a NFp of the first communication network, wherein the service request comprises a network identifier of the second communication network and at least one additional network identifier comprising the plurality of equivalent network identifiers; verifying (820) the second communication network at least partly based on the network identifier of the second communication network in the service request and the at least one additional network identifier comprising the plurality of equivalent network identifiers; and sending (830), to the NFc a response to the service request at least partly based on the verification of the second communication network.

28. The method of claim 27 wherein the plurality of equivalent network identifiers of the second communication network in the service request is provided in at least one of:an access token claim of an access token for the service provided by the NFp, a header of the service request.

29. The method of claim 28 wherein the header of the service request is a 3gpp-Sbi- Originating-Network-Id header.

30. The method of any of claims 28-29, wherein the second communication network is successfully verified when the network identifier of the second communication network in the service request is equal to at least one equivalent network identifier from the plurality of equivalent network identifiers of the second communication network in the access token claim of the access token for the service provided by the NFp, and / or the network identifier of the second communication network in the service request is equal to at least one equivalent network identifier from the plurality of equivalent network identifiers of the second communication network in the header of the service request.

31. The method of any of claims 27-30, wherein the first and / or the second communication network is a Public Land Mobile Network, PLMN.

32. The method of any of claims 27-31 wherein the first and / or the second communication network is a Standalone Non-Public Network, SNPN.

33. A Network Repository Function (1108, 1300), NRF, of a communication network (304, 1102), the NRF being configured to: receive from aNetwork Function service consumer (1108, 1300), NFc, of a second communication network (302, 1102) having a plurality of equivalent network identifiers, an access token request, the access token request comprising the plurality of equivalent network identifiers, wherein the access token request is a request for an access token for a service provided by a Network Function service producer (1108, 1300), NFp, of the first communication network (304, 1102); generate the access token comprising a claim with the plurality of equivalent network identifiers of the second communication network; and send the access token towards the NFc.

34. A Network Function service consumer (1108, 1300), NFc, of a second communication network (302, 1102), the NFc being configured to: send, to a Network Repository Function (1108, 1300), NRF, an access token request, wherein the access token request comprises the plurality of equivalent network identifiers of the second communication network; receive from the NRF an access token, wherein an access token claim comprises the plurality of equivalent network identifiers of the second communication network; send, to a Network Function service producer (1108, 1300), NFp, of a first communication network (304, 1102), a service request for a service provided by the NFp, wherein the service request comprises the access token with the access token claim comprising the plurality of equivalent network identifiers of the second communication network; and receive, from the NFp, a response upon successful verification of the second communication network at least partly based on at least one of: the access token, at least one additional identifier of the plurality of equivalent network identifiers of the second communication network.

35. A network node (1108, 1300) of a second communication network (302, 1102), the communication network having a plurality of equivalent network identifiers, the network node being configured to: receive from a Network Function service consumer, NFc, in the second communication network, a service request for a service provided by a Network Function Service Producer, NFp, wherein the service request comprises an access token with an access token claim comprising the plurality of equivalent network identifiers of the second communication network; generate a header to be attached to the service request, the header comprising the plurality of equivalent network identifiers of the second communication network, if the service request has no header comprising the plurality of equivalent network identifiers of the second communication network; and send the service request with the generated header to the NFp.

36. A Security Edge Protection Proxy (1108, 1300), SEPP, of a first communication network(304, 1102), the SEPP being configured to; receive, via a SEPP of a second communication network (302, 1102), the second communication network having a plurality of equivalent network identifiers, a service request from a Network Function service consumer, NFc, for a service provided by a Network Function service producer, NFp, the service request comprising a plurality of equivalent network identifiers of the second communication network; obtain at least one additional identifier of the second communication network; verify the second communication network at least partly based on the plurality of equivalent network identifiers of the second communication network in the service request and the at least one additional identifier of the second communication network; and send to the NFp, the service request upon successful verification of the second communication network.

37. A Network Function service producer (1108, 1300), NFp, of a first communication network (304, 1102), the NFp being configured to: receive, from a Network Function service consumer (1108, 1300), NFc, of a second communication network(302, 1102), the second communication network having a plurality of equivalent network identifiers, a service request for a service provided by a NFp of the first communication network, wherein the service request comprises a network identifier of the second communication network and at least one additional network identifier comprising the plurality of equivalent network identifiers; verify the second communication network at least partly based on the network identifier of the second communication network in the service request and the at least one additional network identifier comprising the plurality of equivalent network identifiers; and send, to the NFc a response to the service request at least partly based on the verification of the second communication network.

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