Method, apparatus and computer program

Abstract

A network function (i.e. equipment identity register, EIR) comprising means for: receiving, from a second network function (an access and mobility management function, AMF or mobility management entit

Description

Technical Field Various example embodiments of this disclosure relate to methods, apparatuses, and computer programs for a communication network. Background A communication network can be seen as a facility that enables communications between two or more communication devices, or provides communication devices access to a data network. A mobile or wireless communication network is one example of a communication network. A communication device may be provided with a service by an application server. Such communication networks operate in accordance with standards, such as those provided by 3GPP (Third Generation Partnership Project) or ETSI (European Telecommunications Standards Institute). Examples of standards are the so-called 5G (5th Generation) standards promulgated by 3GPP. Summary Some example embodiments of this disclosure will be described with respect to certain aspects. These aspects are not intended to indicate key or essential features of the example embodiments of this disclosure, nor are they intended to be used to limit the scope of thereof. Other features, aspects, and elements will be readily apparent to a person skilled in the art in view of this disclosure. For example, it should be appreciated that further aspects may be provided by the combination of any two or more of the various aspects described below. According to an aspect, there is provided an apparatus comprising means for: receiving, from a second network function, an indication of a permanent equipment identifier; storing information associated with the indication of the permanent equipment identifier received from the second network function; receiving an indication of a status associated with the permanent equipment identifier; and based on the information, providing, to the second network function, an indication related to the status associated with the permanent equipment identifier. In some example embodiments, the indication of the status associated with the permanent equipment identifier is an indication that the status has changed to a status indicating that the permanent equipment identifier is prohibited. In some example embodiments, the means are further for: based on the indication of the status that has been received, generating or updating a record associated with the permanent equipment identifier, the record for the permanent equipment identifier including the status of the permanent equipment identifier. In some example embodiments, the status indicating that the permanent equipment identifier is prohibited means that the permanent equipment identifier is blocked or restricted from use. In some example embodiments, the storing of the information comprises: storing, based on the indication of the permanent equipment identifier, an association between the second network function and the permanent equipment identifier, wherein the indication related to the status associated with the permanent equipment identifier provided to the second network function is based on the association. In some example embodiments, the indication related to the status associated with the permanent equipment identifier comprises: a request for the second network function to deregister a subscriber associated with the permanent equipment identifier. In some example embodiments, the storing of the information comprises: means for storing, based on the indication of the permanent equipment identifier, a subscription, for the second network function, to changes in status associated with the permanent equipment identifier, wherein the indication related to the status associated with the permanent equipment identifier being provided to the second network function is based on the subscription. In some example embodiments, the indication related to the status associated with the permanent equipment identifier comprises: an indication that the status associated with the permanent equipment identifier has changed, and an indication of the status associated with the permanent equipment identifier. In some example embodiments, the indication of the permanent equipment identifier is received in a request for a status associated with the permanent equipment identifier. In some example embodiments, the means are for: based on the indication of the permanent equipment identifier, determining whether there is a record for the permanent equipment identifier; and based on the determining, providing, to the second network function, the status associated with the permanent equipment identifier from the record for the permanent equipment identifier. In some example embodiments, the indication of the permanent equipment identifier is received in a request for subscription to notifications related to the status associated with the permanent equipment identifier. In some example embodiments, the means are further for: in response to receiving the request for subscription to a status associated with the permanent equipment identifier, providing, to the second network function, one of: the status associated with the permanent equipment identifier from the record for the permanent equipment identifier, or an indication that there is no stored record available for the permanent equipment identifier. In some example embodiments, the indication of the status associated with the permanent equipment identifier is received from an operations, administration and maintenance service. In some example embodiments, the means for further for: deleting the information associated with the indication of the permanent equipment identifier received from the second network function based on one of: a request to delete the information being received from the second network function; or an indication of the permanent equipment identifier being received from a third network function In some example embodiments, the apparatus for a network function. In some example embodiments, the at least one of the following: the network function is an equipment identity register, the second network function is an access and mobility management function, the second network function is a mobility management entity, the third network function is a further access and mobility management function, or the third network function is a further mobility management entity. According to an aspect, there is provided an apparatus comprising means for: providing, to a network function, an indication of a permanent equipment identifier; and receiving, from the network function, an indication related to a status associated with the permanent equipment identifier. In some example embodiments, the indication related to a status associated with the permanent equipment identifier received from the network function comprises: a request for the second network function to deregister a subscriber associated with the permanent equipment identifier. In some example embodiments, the indication related to a status associated with the permanent equipment identifier received from the network function comprises: an indication that the status associated with the permanent equipment identifier has changed, and an indication of the status associated with the permanent equipment identifier. In some example embodiments, the indication related to a status associated with the permanent equipment identifier received from the network function comprises: an indication that the status has changed to a status indicating that the permanent equipment identifier is prohibited. In some example embodiments, the providing, to a network function, an indication of a permanent equipment identifier comprises: providing, to the network function, a request for subscription to notifications related to the status associated with the permanent equipment identifier. In some example embodiments, the request comprises: an indication for the status of the permanent equipment identifier that is currently stored to be provided. In some example embodiments, the means are further for: based on the request, receiving, from the network function, one of: the status associated with the permanent equipment identifier from a record for the permanent equipment identifier, or an indication that there is no stored record available for the permanent equipment identifier. In some example embodiments, the means are further for: providing, to the network function, a request to delete information that is stored at the network function related to the second network function and the permanent equipment identifier. In some example embodiments, the apparatus is for a second network function. In some example embodiments, the at least one of the following: the network function is an equipment identity register, the second network function is an access and mobility management function, the second network function is a mobility management entity, the third network function is a further access and mobility management function, or the third network function is a further mobility management entity. According to an aspect, there is provided a method comprising: receiving, from a second network function, an indication of a permanent equipment identifier; storing information associated with the indication of the permanent equipment identifier received from the second network function; receiving an indication of a status associated with the permanent equipment identifier; and based on the information, providing, to the second network function, an indication related to the status associated with the permanent equipment identifier. In some example embodiments, the indication of the status associated with the permanent equipment identifier is an indication that the status has changed to a status indicating that the permanent equipment identifier is prohibited. In some example embodiments, the method comprises: based on the indication of the status that has been received, generating or updating a record associated with the permanent equipment identifier, the record for the permanent equipment identifier including the status of the permanent equipment identifier. In some example embodiments, the status indicating that the permanent equipment identifier is prohibited means that the permanent equipment identifier is blocked or restricted from use. In some example embodiments, the storing of the information comprises: storing, based on the indication of the permanent equipment identifier, an association between the second network function and the permanent equipment identifier, wherein the indication related to the status associated with the permanent equipment identifier provided to the second network function is based on the association. In some example embodiments, the indication related to the status associated with the permanent equipment identifier comprises: a request for the second network function to deregister a subscriber associated with the permanent equipment identifier. In some example embodiments, the storing of the information comprises: storing, based on the indication of the permanent equipment identifier, a subscription, for the second network function, to changes in status associated with the permanent equipment identifier, wherein the indication related to the status associated with the permanent equipment identifier being provided to the second network function is based on the subscription. In some example embodiments, the indication related to the status associated with the permanent equipment identifier comprises: an indication that the status associated with the permanent equipment identifier has changed, and an indication of the status associated with the permanent equipment identifier. In some example embodiments, the indication of the permanent equipment identifier is received in a request for a status associated with the permanent equipment identifier. In some example embodiments, the method comprises: based on the indication of the permanent equipment identifier, determining whether there is a record for the permanent equipment identifier; and based on the determining, providing, to the second network function, the status associated with the permanent equipment identifier from the record for the permanent equipment identifier. In some example embodiments, the indication of the permanent equipment identifier is received in a request for subscription to notifications related to the status associated with the permanent equipment identifier. In some example embodiments, the method comprises: in response to receiving the request for subscription to a status associated with the permanent equipment identifier, providing, to the second network function, one of: the status associated with the permanent equipment identifier from the record for the permanent equipment identifier, or an indication that there is no stored record available for the permanent equipment identifier. In some example embodiments, the indication of the status associated with the permanent equipment identifier is received from an operations, administration and maintenance service. In some example embodiments, the method comprises: deleting the information associated with the indication of the permanent equipment identifier received from the second network function based on one of: a request to delete the information being received from the second network function; or an indication of the permanent equipment identifier being received from a third network function. In some example embodiments, the method is performed by a network function. In some example embodiments, the at least one of the following: the network function is an equipment identity register, the second network function is an access and mobility management function, the second network function is a mobility management entity, the third network function is a further access and mobility management function, or the third network function is a further mobility management entity. According to an aspect, there is provided a method comprising: providing, to a network function, an indication of a permanent equipment identifier; and receiving, from the network function, an indication related to a status associated with the permanent equipment identifier. In some example embodiments, the indication related to a status associated with the permanent equipment identifier received from the network function comprises: a request for the second network function to deregister a subscriber associated with the permanent equipment identifier. In some example embodiments, the indication related to a status associated with the permanent equipment identifier received from the network function comprises: an indication that the status associated with the permanent equipment identifier has changed, and an indication of the status associated with the permanent equipment identifier. In some example embodiments, the indication related to a status associated with the permanent equipment identifier received from the network function comprises: an indication that the status has changed to a status indicating that the permanent equipment identifier is prohibited. In some example embodiments, the providing, to a network function, an indication of a permanent equipment identifier comprises: providing, to the network function, a request for subscription to notifications related to the status associated with the permanent equipment identifier. In some example embodiments, the request comprises: an indication for the status of the permanent equipment identifier that is currently stored to be provided. In some example embodiments, the method comprises: based on the request, receiving, from the network function, one of: the status associated with the permanent equipment identifier from a record for the permanent equipment identifier, or an indication that there is no stored record available for the permanent equipment identifier. In some example embodiments, the method comprises: providing, to the network function, a request to delete information that is stored at the network function related to the second network function and the permanent equipment identifier. In some example embodiments, the method is performed by a second network function. In some example embodiments, the at least one of the following: the network function is an equipment identity register, the second network function is an access and mobility management function, the second network function is a mobility management entity, the third network function is a further access and mobility management function, or the third network function is a further mobility management entity. According to an aspect, there is provided an apparatus comprising: at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to perform: receiving, from a second network function, an indication of a permanent equipment identifier; storing information associated with the indication of the permanent equipment identifier received from the second network function; receiving an indication of a status associated with the permanent equipment identifier; and based on the information, providing, to the second network function, an indication related to the status associated with the permanent equipment identifier. In some example embodiments, the indication of the status associated with the permanent equipment identifier is an indication that the status has changed to a status indicating that the permanent equipment identifier is prohibited. In some example embodiments, the apparatus is caused to perform: based on the indication of the status that has been received, generating or updating a record associated with the permanent equipment identifier, the record for the permanent equipment identifier including the status of the permanent equipment identifier. In some example embodiments, the status indicating that the permanent equipment identifier is prohibited means that the permanent equipment identifier is blocked or restricted from use. In some example embodiments, the storing of the information comprises: storing, based on the indication of the permanent equipment identifier, an association between the second network function and the permanent equipment identifier, wherein the indication related to the status associated with the permanent equipment identifier provided to the second network function is based on the association. In some example embodiments, the indication related to the status associated with the permanent equipment identifier comprises: a request for the second network function to deregister a subscriber associated with the permanent equipment identifier. In some example embodiments, the storing of the information comprises: storing, based on the indication of the permanent equipment identifier, a subscription, for the second network function, to changes in status associated with the permanent equipment identifier, wherein the indication related to the status associated with the permanent equipment identifier being provided to the second network function is based on the subscription. In some example embodiments, the indication related to the status associated with the permanent equipment identifier comprises: an indication that the status associated with the permanent equipment identifier has changed, and an indication of the status associated with the permanent equipment identifier. In some example embodiments, the indication of the permanent equipment identifier is received in a request for a status associated with the permanent equipment identifier. In some example embodiments, the apparatus is caused to perform: based on the indication of the permanent equipment identifier, determining whether there is a record for the permanent equipment identifier; and based on the determining, providing, to the second network function, the status associated with the permanent equipment identifier from the record for the permanent equipment identifier. In some example embodiments, the indication of the permanent equipment identifier is received in a request for subscription to notifications related to the status associated with the permanent equipment identifier. In some example embodiments, the apparatus is caused to perform: in response to receiving the request for subscription to a status associated with the permanent equipment identifier, providing, to the second network function, one of: the status associated with the permanent equipment identifier from the record for the permanent equipment identifier, or an indication that there is no stored record available for the permanent equipment identifier. In some example embodiments, the indication of the status associated with the permanent equipment identifier is received from an operations, administration and maintenance service. In some example embodiments, the apparatus is caused to perform: deleting the information associated with the indication of the permanent equipment identifier received from the second network function based on one of: a request to delete the information being received from the second network function; or an indication of the permanent equipment identifier being received from a third network function. In some example embodiments, the apparatus is for a network function. In some example embodiments, the at least one of the following: the network function is an equipment identity register, the second network function is an access and mobility management function, the second network function is a mobility management entity, the third network function is a further access and mobility management function, or the third network function is a further mobility management entity. According to an aspect, there is provided an apparatus comprising: at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to perform: providing, to a network function, an indication of a permanent equipment identifier; and receiving, from the network function, an indication related to a status associated with the permanent equipment identifier. In some example embodiments, the indication related to a status associated with the permanent equipment identifier received from the network function comprises: a request for the second network function to deregister a subscriber associated with the permanent equipment identifier. In some example embodiments, the indication related to a status associated with the permanent equipment identifier received from the network function comprises: an indication that the status associated with the permanent equipment identifier has changed, and an indication of the status associated with the permanent equipment identifier. In some example embodiments, the indication related to a status associated with the permanent equipment identifier received from the network function comprises: an indication that the status has changed to a status indicating that the permanent equipment identifier is prohibited. In some example embodiments, the providing, to a network function, an indication of a permanent equipment identifier comprises: providing, to the network function, a request for subscription to notifications related to the status associated with the permanent equipment identifier. In some example embodiments, the request comprises: an indication for the status of the permanent equipment identifier that is currently stored to be provided. In some example embodiments, the apparatus is caused to perform: based on the request, receiving, from the network function, one of: the status associated with the permanent equipment identifier from a record for the permanent equipment identifier, or an indication that there is no stored record available for the permanent equipment identifier. In some example embodiments, the apparatus is caused to perform: providing, to the network function, a request to delete information that is stored at the network function related to the second network function and the permanent equipment identifier. In some example embodiments, the apparatus is for a second network function. In some example embodiments, the at least one of the following: the network function is an equipment identity register, the second network function is an access and mobility management function, the second network function is a mobility management entity, the third network function is a further access and mobility management function, or the third network function is a further mobility management entity. According to an aspect, there is provided an apparatus comprising: circuitry configured to perform: receiving, from a second network function, an indication of a permanent equipment identifier; circuitry configured to perform: storing information associated with the indication of the permanent equipment identifier received from the second network function; circuitry configured to perform: receiving an indication of a status associated with the permanent equipment identifier; and circuitry configured to perform: based on the information, providing, to the second network function, an indication related to the status associated with the permanent equipment identifier. According to an aspect, there is provided an apparatus comprising: circuitry configured to perform: providing, to a network function, an indication of a permanent equipment identifier; and circuitry configured to perform: receiving, from the network function, an indication related to a status associated with the permanent equipment identifier. According to an aspect, there is provided a computer program comprising instructions, which when executed by an apparatus, cause the apparatus to perform at least the following: receiving, from a second network function, an indication of a permanent equipment identifier; storing information associated with the indication of the permanent equipment identifier received from the second network function; receiving an indication of a status associated with the permanent equipment identifier; and based on the information, providing, to the second network function, an indication related to the status associated with the permanent equipment identifier. According to an aspect, there is provided a computer program comprising instructions, which when executed by an apparatus, cause the apparatus to perform at least the following: providing, to a network function, an indication of a permanent equipment identifier; and receiving, from the network function, an indication related to a status associated with the permanent equipment identifier. A computer product stored on a medium may cause an apparatus to perform the methods as described herein. A non-transitory computer readable medium comprising program instructions, that, when executed by an apparatus, cause the apparatus to perform the methods (or portions thereof) as described herein. An electronic device may comprise apparatus as described herein. Various other aspects and further example embodiments are also described in the following detailed description and in the attached claims. According to some aspects, there is provided the subject matter of the independent claims. Some further aspects are defined in the dependent claims. Any example embodiments that do not fall under the scope of the claims (if any) are to be interpreted as examples useful for understanding the disclosure. List of Abbreviations: AF: Application Function AMF: Access and Mobility Management Function AN: Access Network BS: Base Station CN: Core Network DL: Downlink EIR: Equipment identity register eNB: eNodeB gNB: gNodeB HTTP: Hypertext transfer protocol lloT: Industrial Internet of Things LTE: Long Term Evolution NEF: Network Exposure Function NG-RAN: Next Generation Radio Access Network NF: Network Function NR: New Radio NRF: Network Repository Function NW: Network MME: Mobility management entity MS: Mobile Station PCF Policy Control Function PEI: Permanent equipment identifier PLMN: Public Land Mobile Network OAM: Operations, administration and maintenance RAN: Radio Access Network RF: Radio Frequency SMF: Session Management Function SUPI: Subscription permanent identity UE: User Equipment UDR: Unified Data Repository UDSF: Unstructured data storage function UDM: Unified Data Management UL: Uplink UPF: User Plane Function 3GPP: 3rd Generation Partnership Project 5G: 5th Generation 5GC: 5G Core network 5G-AN: 5G Radio Access Network 5GS: 5G System Brief Description of Drawings Some example embodiments will now be described, by way of illustrative and nonlimiting example only, with reference to the accompanying drawings in which: FIG. 1 shows a schematic representation of a 5G communication system; FIG. 2 shows a schematic representation of an apparatus for the 5G communication system of FIG. 1; FIG. 3 shows a schematic representation of a communication device of the 5G communication system of FIG. 1; FIG. 4 shows an example signalling and operations diagram between network functions associated with an equipment identity register service according to some example embodiments of the disclosure; FIG. 5 shows another example signalling and operations diagram between network functions associated with an equipment identity register service according to some example embodiments of the disclosure; FIG. 6 shows another example signalling and operations diagram between network functions associated with an equipment identity register service according to some example embodiments of the disclosure; FIG. 7 shows another example signalling and operations diagram between network functions associated with an equipment identity register service according to some example embodiments of the disclosure; FIG. 8 shows another example signalling and operations diagram between network functions associated with an equipment identity register service according to some example embodiments of the disclosure; FIG. 9 shows another example signalling and operations diagram between network functions associated with an equipment identity register service according to some example embodiments of the disclosure; FIG. 10 shows another example signalling and operations diagram between network functions associated with an equipment identity register service according to some example embodiments of the disclosure; FIG. 11 shows another example signalling and operations diagram between network functions associated with an equipment identity register service according to some example embodiments of the disclosure; FIG. 12 shows another example signalling and operations diagram between network functions associated with an equipment identity register service according to some example embodiments of the disclosure; FIG. 13 shows an example method flow diagram performed by an apparatus according to some example embodiments of the disclosure; FIG. 14 shows another example method flow diagram performed by an apparatus according to some example embodiments of the disclosure; and FIG. 15 shows a schematic representation of a non-volatile memory medium storing instructions which when executed by a processor allow a processor to perform one or more of the methods (or portions thereof) of FIGS. 13 to 14. Detailed Description In 5G networks, an equipment identity register (EIR) is defined. The EIR is a core network function (NF) that supports the functionality of checking the status of a mobile equipment or user equipment using the equipment’s permanent identifier (e.g., to check that it has not been prohibited from use). A reference point N17 is used for interactions between the EIR and an Access and Mobility Management Function (AMF) enabling the checking of the status of the mobile equipment (ME) identity. During any procedure establishing a signalling connection with a UE, the network may perform an ME identity check with EIR via an ‘N5g-eir_EquipmentldentityCheck’ service exhibited by 5G-EIR. The 'N5g-eir_EquipmentldentityCheck’ service may be utilised to determine whether an ME / UE has been blacklisted. In this manner, the EIR is a repository for device records representing devices (e.g., MEs, UEs) that may have been specified as ‘permitted’, ‘restricted’ or ‘tracked’. A ‘restricted’ equipment may be referred to as blacklisted. For example, if a network access device is reported as stolen, a record for this device may be added to the EIR that marks this device as restricted (or blacklisted). The records in the EIR may be checked by an AMF each time a request for a UE to register on the network is processed. If the EIR record exists for the device and the status is set to restricted / blacklisted, the AMF may reject the registration request. The records in the EIR are identified using a permanent equipment identifier (PEI). A PEI is globally unique to a device. The PEI is supplied by the device to the AMF when network registration is attempted. In 5G, the PEI is the means by which the network identifies the UE. For devices that are capable of accessing a 3GPP network, the PEI is an international mobile equipment identity (IMEI). An EIR may be interrogated by AMF when processing a network registration attempt. If a communication device (e.g., ME, UE) attempting registration is recorded in the EIR as restricted, the AMF may reject the registration attempt. In this manner, communication devices that are banned from accessing the network are prevented from registering subsequently. For example, a communication device may be banned from accessing the network following a report that the communication device has been stolen. In this context, it should be understood that the terms ‘restricted’, ‘prohibited’, ‘blacklisted’, and ‘blocked’ may be used interchangeably. These terms are used to describe communication devices that are prohibited from accessing a network. When a communication device is to be recorded as restricted, a record for the communication device may be generated, or added to, or updated in, the EIR. Any subsequent attempt to register that communication device with the network can be blocked (assuming the access and mobility management function (AMF) checks the EIR). However, there may be a lag (time duration) between the communication device being marked as restricted and the communication device attempting to register again. During this period, the communication device is still able to obtain network services. Certain challenges arise in deregistering the communication device as soon as the record is updated to be restricted in the EIR. In principle, this could be achieved by the EIR initiating a deregistration at the AMF as soon as the record of the communication device is set to restricted. The EIR initiating a deregistration at the AMF may utilize the unified data management (UDM) mechanism as follows: 1) EIR sends a request to UDM containing the PEI of the communication device to be deregistered, 2) the UDM determines a subscriber currently associated with the PEI, 3) the UDM determines the AMF currently serving the subscriber, 4) the UDM sends a deregistration request to the AMF containing the subscriber ID, and 5) the AMF deregisters the subscriber. This mechanism involves the UDM looking up the subscriber currently associated with the PEI of the communication device to be deregistered. This could be performed by requesting a unified data repository (UDR) to search all subscriber context (registration) information to find the subscriber record containing the PEI. However, the UDR may not support searching of subscriber records based on PEI. Furthermore, there is no support on the UDR interface (Nudr) for requesting subscriber information based on PEI. Furthermore, if there are multiple UDRs in the network, all of them are searched for the PEI. Therefore, there are a number of problems associated with deregistering the communication device using this mechanism. Another way for the UDM to look up the subscriber currently associated with the PEI of the communication device to be deregistered is to perform a search of a secondary data store of associations between PEIs and subscribers and / or AMFs. However, for this method to be used, a secondary data store holding associations between devices and subscribers and / or AMFs would have to be maintained. This involves duplication of data and problems associated therewith (e.g., the PEI may already be associated with a subscriber in UDR). Furthermore, this would also mean maintaining the secondary data store of associations and involve a database update each time an AMF performs a registration. There is no standardized mechanism for storing this association data. Therefore, there are a number of problems associated with deregistering the communication device using this mechanism. Any of the various example embodiments of this disclosure may address (at least in part) one or more of the problems either explicitly described herein or otherwise apparent to one skilled in the art in view of this disclosure. In some example embodiments, there is provided an apparatus that is configured for (e.g., comprising means for performing and / or comprising at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to perform) receiving, from a second network function (e.g., an AMF or MME), an indication of a permanent equipment identifier, and then storing information associated with the indication of the permanent equipment identifier received from the second network function. The apparatus also configured for receiving an indication of a status associated with the permanent equipment identifier, and based on the information, providing, to the second network function, an indication related to the status associated with the permanent equipment identifier. In this manner, deregistration requests or indications associated with deregistration are initiated by EIR, using a store of information between PEIs and subscribers and / or AMFs, that is separate from stored UDR subscriber data, without requiring extra signalling to maintain the data store whenever an AMF registers a subscriber. In some example embodiments, an existing EIR service operation, namely CheckEquipmentldentity, which is used for checking for a record in EIR holding the status of the device (e.g., restricted (or BLACKLISTED), tracked (or GREYLISTED), permitted (or WHITELISTED) is also utilised for deregistering a blacklisted communication device. This EIR service operation is performed by an AMF each time a communication device attempts to register on the network. In some example embodiments, CheckEquipmentldentity is used to store an association in the EIR that may be subsequently used by the EIR when it is to send a deregistration request to AMF when a device is marked as blacklisted / blocked. EIR behaviour may be extended so that when a CheckEquipmentldentity request is processed, the EIR stores an association between the PEI received in the request and the AMF that sent the request. In some example embodiments, the association also includes an identity of a subscriber (e.g., a subscriber ID). When the EIR is updated with a record that marks a device as blacklisted / blocked, the EIR searches for an association for that device. When an association is found, the EIR sends a deregistration request directly to the AMF indicated in the association. AMF behaviour and associated interface (with the EIR) may be extended to accept a deregistration request from EIR and locate the device registration using the PEI sent by EIR in the request so to remove it. In some example embodiments, a new service operation is configured for an EIR, which allows an AMF to subscribe to notifications on an equipment identity record in the EIR. The subscription request creates a subscription to notifications, whereby the subscription acts as an association between PEI and AMF (to be stored in the EIR). The subscription may be created based on whether an equipment identity record for the PEI exists in the EIR or not. This allows notifications to be sent when an equipment identity record is created, as well as when the equipment identity record is updated or deleted. In some example embodiments, the subscription operation may specify an ‘immediate report’ parameter to request the current state of the equipment identity record for the PEI. If this parameter is included, the EIR sends the content of the equipment identity record for the PEI in the response to the subscription request. If no record currently exists, this can be indicated in the response to the subscription request. In example embodiments where the immediate report parameter is used in the subscription request, the subscription request may be used as an alternative to a CheckEquipmentldentity operation, as it achieves both the subscription and the retrieval of the current status in a single operation. In some example embodiments, the CheckEquipmentldentity operation and the subscription to notifications are both used (separately). In some example embodiments, EIR behaviour is extended so that when the EIR is updated with a record that marks a device as blocked (or changes the status of a communication device) the EIR sends a notification (directly) to the AMF that has subscribed to notifications on that communication device. In some example embodiments, AMF behaviour and the interface to EIR are extended to accept notifications of equipment status change and locate the communication device registration using the PEI sent by EIR in the notification and remove it. Before explaining in further detail the various example embodiments, certain general aspects of a wireless communication system and communication devices capable of utilising EIR services are briefly explained with reference to FIGS. 1 to 3 to assist in understanding the technology underlying the described example embodiments. For example, an EIR and an AMF of a 5G communication system (as shown in FIG. 1) capable of communicating with each other is described. Furthermore, a communication device (as shown in FIG. 3) capable of being assigned an equipment status (e.g., permitted, prohibited, etc.) is described. FIG. 1 shows a schematic representation of a 5G communication system 100. The wireless communication system 100 comprises one more communication devices 102, such as user equipments (UEs) or terminals. The wireless communication system 100 comprises a 5G system (5GS). The 5GS comprises a 5G radio access network (5G-RAN) 106, a 5G core network (5GC) 104 comprising one or more network functions (NF), one or more application functions (AFs) 108, and one or more data networks (DNs) 110. The 5G-RAN 106 may comprise one or more gNodeB (gNB) distributed unit (DU) functions connected to one or more gNodeB (gNB) centralized unit (CU) functions. The 5GC 104 comprises an access and mobility management function (AMF) 112, a session management function (SMF) 114, an authentication server function (ALISF) 116, a user data management (UDM) 118, a user plane function (UPF) 120, a network exposure function (NEF) 122, an EIR 124 and / or other NFs. Some of the various example embodiments as shown below (and described herein) may be applicable to 3GPP 5G standards. Additionally or alternatively, some of the various example embodiments may also be applicable to6G, 5G-advanced, 4G, 3G and other 3GPP standards. In a wireless communication system 100 (such as that shown in FIG. 1), communication devices 102, such as terminals, user apparatuses, user equipments (UE), and / or machine-type communication devices, are provided with wireless access via at least wireless transmitting and / or receiving node or point (e.g., base station). The communication device 102 is provided with an appropriate signal receiving and transmitting apparatus for enabling (or otherwise facilitating) communications, for example enabling (or otherwise facilitating) access to a communication network or communications directly with other devices. The communication device 102 may access a carrier provided by a base station or access point, and transmit and / or receive communications via the carrier. FIG. 2 illustrates an example of an apparatus 200. The apparatus 200 may be for the 5G communication system of FIG. 1. The apparatus 200 may be for controlling a function of one or more network entities and / or network functions, such as the entities of the 5G-RAN or the 5GC as illustrated on FIG. 1. The apparatus 200 comprises at least one random access memory (RAM) 211a, at least one read only memory (ROM) 211b, at least one processor 212, 213 and an input / output interface 214. The at least one processor 212, 213 is coupled to the RAM 211a and the ROM 211b. The at least one processor 212, 213 may be configured to execute an appropriate software code 215. The software code 215 may, for example, enable (or otherwise facilitate) the performance of any of the aspects described herein or various example embodiments (including any portions thereof) of this disclosure. The software code 215 may be stored in the ROM 211b. The apparatus 200 may be interconnected with another apparatus 200 controlling another entity / function of the 5G-AN or the 5GC. In some example embodiments, apparatus 200 may be configured to perform one or more functions of the 5G-AN or the 5GC. For example, apparatus 200 may be configured to perform at least some functionality of a particular function of the 5G-AN or the 5GC. For example, apparatus 200 may be configured to operate as a particular function of the 5G-AN or the 5GC. In alternative examples, apparatus 200 may be configured to perform at least some functionality of two or more functions of the 5G-AN and / or the 5GC. For example, apparatus 200 may be configured to operate as two or more functions of the 5G-AN and / or the 5GC. The apparatus 200 may comprise one or more circuits or circuitry (not shown), which may be configured to perform any of the aspects described herein or various example embodiments (including any portions thereof) of this disclosure. FIG. 3 illustrates an example of a communication device 300. The communication device 300 may be similar to the communication device 102 illustrated in FIG. 1. The communication device 300 may be provided by any device capable of sending and receiving radio signals. Non-limiting and illustrative examples of a communication device 300 include a user equipment (UE), a terminal, a mobile station (MS) or mobile device (such as, a mobile phone or what is known as a ’smart phone’), a computer provided with a wireless interface card or other wireless interface facility (e.g., USB dongle), a personal data assistant (PDA) or a tablet provided with wireless communication capabilities, a machine-type communications (MTC) device, a Cellular Internet of things (CloT) device, or a terrestrial / maritime / aerial vehicle (such as a car, a truck, a boat, an air plane, or a drone, or any combinations of these or the like). The communication device 300 may provide, for example, communication of data for carrying communications. The communications may be one or more of voice, electronic mail (email), text message, multimedia, data, machine data and so on. The communication device 300 may receive signals over an air or radio interface 307 via appropriate apparatus for receiving and may transmit signals via appropriate apparatus for transmitting radio signals. In FIG. 3, a transceiver apparatus is designated schematically by block 306. The transceiver apparatus 306 may be provided, for example by means of a radio part and associated antenna arrangement. The antenna arrangement may be arranged internally and / or externally to the mobile device. The communication device 300 may be provided with at least one processor 301, at least one memory ROM 302a, at least one RAM 302b and other possible components 303 for use in software and hardware aided execution of tasks it is designed to perform, including control of access to and communications with access systems and other communication devices. The at least one processor 301 is coupled to the RAM 302b and the ROM 302a. The at least one processor 301 may be configured to execute an appropriate software code 308. The software code 308 may, for example, enable (or otherwise facilitate) performance of any of the aspects described herein or various example embodiments (including any portions thereof) of this disclosure. The software code 308 may be stored in the ROM 302a. The communication device 300 may comprise one or more circuits, or circuitry (not shown) which may be configured to perform any of the aspects described herein or various example embodiments (including any portions thereof) of this disclosure. The processor, storage and other relevant control apparatus may be provided on an appropriate circuit board and / or in chipsets. This feature is denoted by reference 304. The communication device 300 (e.g., a UE) may comprise mobile equipment (ME) and a universal integrated circuit card (UICC) (not shown). The UICC may comprise one or more applications, such as a universal subscriber identity module (USIM). The USIM stores (e.g., securely) and handles sensitive data related to a subscriber and a home network (HN). The communication device 300 may optionally have a user interface, such as keypad 305, touch sensitive screen or pad, combinations thereof or the like. Optionally one or more of a display, a speaker and a microphone may be provided (e.g., equipped) depending on the type of the device. FIG. 4 shows an example signalling and operations diagram between network functions associated with an equipment identity register service according to some example embodiments of the disclosure. In some example embodiments, there are communications between an AMF, EIR, and operations, administration and maintenance (OAM). The EIR may be referred to as an NF / first NF. The AMF may be referred to as a further NF / second NF. In other example embodiments, a mobility management entity (MME) may replace the AMF. In other example embodiments, an NF or other network service may replace the OAM. At S401, the AMF provides an indication of a PEI to the EIR. The indication may be a request for an equipment status for the PEI. For example, the AMF may provide ‘GET... / equipment-status?pei={pei}’ to the EIR. ‘GET... / equipment-status?pei={pei}’ is a representation of an hypertext transfer protocol (HTTP) request, of method type GET including the URI of the target resource, ... / equipment-status?pei={pei}, although in some example embodiments the first part of the URI has been replaced with an ellipsis for clarity. The URI contains a query parameter (the part following the '?’), and follows the format defined in RFC3986. The EIR determines, based on the PEI, whether there is a record for the PEI that is accessible to the EIR. At S402a, when there is no record for the PEI, the EIR provides an indication to the AMF that the PEI was not found. For example, the EIR may provide ‘404 Not found’ to the AMF. At S402b, when there is a record for the PEI, the EIR accesses the record and determines the associated status (or equipment status) for the PEI. The EIR provides, to the AMF, an indication of the status for the PEI. In some example embodiments, the EIR provides an indication that the PEI is permitted. For example, the EIR may provide ‘OK EirResponseData (“WHITELISTED”)’ to the AMF. At S403, the EIR stores information related to the PEI that was received from the AMF. The EIR may store an association between the AMF and PEI. For example, an identity of the AMF (‘AMF ID’) may be associated with the PEI, and stored at a location accessible to the EIR. At S404, the EIR receives an indication of a status for the PEI. The indication of the status for the PEI may be received from the 0AM. In some example embodiments, the received indication is that the device assigned the PEI has been blocked (e.g., prohibited from use). This may be because the communication device (which has the PEI) has been stolen. For example, the EIR receives ‘Block device (PEI={pei})’. In this context, it should be understood that ‘a PEI that has been blocked’ and ‘a device assigned the PEI has been blocked’ have the same meaning. In some example embodiments, the received indication of the status is that a communication device assigned to the PEI has been blocked (e.g., prohibited from use). In some example embodiments, the received indication of the status is that a record representing the communication device assigned to the PEI has been given a blocked status. In example embodiments where the EIR has a record for the PEI (e.g., S402b), this received indication means that the status for the PEI has changed. The status of the PEI has changed from ‘permitted’ to ‘prohibited’. At S405, the EIR determines whether there is a stored association for the PEI that has been indicated as blocked. In this manner, the EIR searches for device-to-AMF associations for the PEI. At S406, the EIR provides, to the AMF, an indication related to the status associated with the PEI. The EIR may provide a request, indicating the PEI, for the AMF to deregister a subscriber. For example, the EIR may provide ‘POST DeregisterDevice ({pei})’ to the AMF. At S407, the AMF provides, to the EIR, an acknowledgement of the indication (of S406). For example, the AMF may provide ‘204 No content’ to the EIR. Therefore, this enables (or otherwise facilitates) an EIR to initiate a deregistration request to the correct AMF (e.g., the AMF currently associated with the PEI) without involving other core network entities, such as UDM and UDR. FIG. 5 shows another example signalling and operations diagram between network functions associated with an equipment identity register service according to some example embodiments of the disclosure. In some example embodiments, there are communications between an AMF, EIR, and OAM. The EIR may be referred to as a NF / first NF. The AMF may be referred to as a further NF / second NF. In other example embodiments, a mobility management entity (MME) may replace the AMF. In other example embodiments, an NF or other network service may replace the OAM. At S501, the AMF provides an indication of a PEI to the ER. The indication may be a request for an equipment status for the PEI. For example, the AMF may provide ‘GET... / equipment-status?pei={pei}’ to the EIR. The EIR determines, based on the PEI, whether there is a record for the PEI that is accessible to the EIR. At S502a, when there is no record for the PEI, the EIR provides an indication to the AMF that the PEI was not found. For example, the EIR may provide ‘404 Not found’ to the AMF. At S502b, when there is a record for the PEI, the EIR accesses the record and determines the associated status (or equipment status) for the PEI. The EIR provides, to the AMF, an indication of the status for the PEI. In some example embodiments, the EIR provides an indication that the PEI is permitted. For example, the EIR may provide ‘OK EirResponseData (“WHITELISTED”)’ to the AMF. At S503, the AMF provides, to the EIR, an indication of the PEI. The indication may be a subscription request for notifications for the PEI. For example, a subscription to notifications, for the PEI, for any changes in status (equipment status). For example, the AMF provides ‘POST ... / equipment-status-subscriptions EquipmentStatusSubscription (pei {pei})’ to the EIR. At S504, the EIR stores information related to the PEI that has been received from the AMF. For example, the EIR creates and stores a subscription, for the AMF, to changes in status associated with the PEI. The creating of the subscription may be performed in response to receiving the subscription request from the AMF. At S505, the EIR provides, to the AMF, an acknowledgement of the indication (of S503). The acknowledgement may be interpreted by the AMF as confirmation of the subscription to notification for the PEI. For example, the EIR may provide ‘204 No content’ to the AMF. At S506, the EIR receives an indication of a status for the PEI. The indication of the status for the PEI may be received from the OAM. In some example embodiments, the received indication is that the device assigned the PEI has been blocked (e.g., prohibited from use). This may be because the communication device (PEI) has been stolen. For example, the EIR receives ‘Block device (PEI={pei})’. In some example embodiments, the received indication of the status is that a communication device assigned to the PEI has been blocked (e.g., prohibited from use). In some example embodiments, the received indication of the status is that a record representing the communication device assigned to the PEI has been given a blocked status. In example embodiments where the EIR has a record for the PEI (e.g., S502b), this received indication means that the status for the PEI has changed. The status of the PEI has changed from ‘permitted’ to ‘prohibited’. At S507, the EIR provides, to the AMF, an indication related to the status associated with the PEI. The EIR may provide a message / notification indicating the (current) status of the PEI. In some example embodiments, the status for the PEI has been changed to prohibited. For example, the EIR may provide ‘POST EquipmentStatusChangeNotif ({pei}, “BLACKLISTED”)’ to the AMF. At S508, the AMF provides an acknowledgement (of the message in S507) to the EIR. For example, the AMF may provide ‘204 No content’ to the EIR. In FIG. 5, the status for the PEI changes from ‘permitted’ to ‘prohibited’. When the EIR is updated with a record that marks the PEI (or device assigned the PEI) as blocked, or changes the status of the PEI (or device assigned the PEI) in any other way, if a subscription to notifications for the device exists, the EIR sends a notification directly to the AMF that has subscribed to notifications on that PEI. In response to receiving the indication that the status is prohibited, the AMF may locate the device registration using the PEI sent in the notification and then initiates deregistration of that device. Therefore, this enables (or otherwise facilitates) an EIR to request an AMF to initiate a deregistration without involving other core network entities, such as UDM and UDR. The involves an extra request from the AMF to subscribe to notifications. FIG. 6 shows another example signalling and operations diagram between network functions associated with an equipment identity register service according to some example embodiments of the disclosure. In some example embodiments, there are communications between an AMF, EIR, and OAM. The EIR may be referred to as an NF / first NF. The AMF may be referred to as a further NF / second NF. In other example embodiments, a mobility management entity (MME) may replace the AMF. In other example embodiments, an NF or other network service may replace the OAM. At S601, the AMF provides an indication of a PEI to the EIR. The indication may be a subscription request for notifications for the PEI. For example, a subscription to notifications, for the PEI, for any changes in status (equipment status). The subscription request also includes an indication for a current status of the PEI to be provided. For example, a parameter (e.g., ‘immediateReport’ parameter) may be marked as ‘TRUE’ in the subscription request to the EIR. For example, the AMF provides ‘POST ... / equipment-status-subscriptions EquipmentStatusSubscription (pei {pei}, immediateReport {true})’ to the EIR. At S602, the EIR stores information related to the PEI that has been received from the AMF. For example, the EIR creates and stores a subscription, for the AMF, to changes in status associated with the PEI. The creating of the subscription may be performed in response to receiving the subscription request from the AMF. As the indication received from the AMF (in S601) included an indication for a current status of the PEI, the EIR determines whether there is a record for the PEI. At S603a, when there is a record accessible to the EIR for the PEI, the EIR provides an indication of the status for the PEI to the AMF. For example, when the PEI is recorded as ‘permitted’, the EIR provides ‘200 OK EirResponseData (immediateReport {“WHITELISTED”})’ to the AMF. At S603b, when there is no record accessible to the EIR for the PEI, the EIR provides an indication that the status for the PEI is unknown, to the AMF. For example, the EIR provides ‘200 OK EirResponseData (immediateReport {“UNKNOWN”})’ to the AMF. At S604, the EIR receives an indication of a status for the PEI. The indication of the status for the PEI may be received from the OAM. In some example embodiments, the received indication is that the device assigned the PEI has been blocked (i.e., prohibited from use). This may be because the communication device (that has the assigned PEI) has been stolen. For example, the EIR receives ‘Block device (PEI={pei})’. In some example embodiments, the received indication of the status is that a communication device assigned to the PEI has been blocked (e.g., prohibited from use). In some example embodiments, the received indication of the status is that a record representing the communication device assigned to the PEI has been given a blocked status. In example embodiments where the EIR has a record for the PEI (e.g., S603b), this received indication means that the status for the PEI has changed. The status of the PEI has changed from ‘permitted’ to ‘prohibited’. At S605, the EIR provides, to the AMF, an indication related to the status associated with the PEI. The EIR may provide a message / notification indicating the (current) status of the PEI. In some example embodiments, the status for the PEI has been changed to prohibited. For example, the EIR may provide ‘POST EquipmentStatusChangeNotif ({pei}, “BLACKLISTED”)’ to the AMF. At S606, the AMF provides an acknowledgement (of the message in S605) to the EIR. For example, the AMF may provide ‘204 No content’ to the EIR. In FIG. 6, the status for the PEI changes from ‘permitted’ to ‘prohibited’. When the EIR is updated with a record that marks the PEI (or device assigned the PEI) as blocked, or changes the status of the PEI (or device assigned the PEI) in any other way, if a subscription to notifications for the device exists, the EIR sends a notification (e.g., directly) to the AMF that has subscribed to notifications on that PEI. In response to receiving the indication that the status is prohibited, the AMF may locate the device registration using the PEI sent in the notification and then initiates deregistration of that device. Therefore, this enables (or otherwise facilitates) an EIR to request an AMF to initiate a deregistration without involving other core network entities, such as UDM and UDR. The example embodiments of FIGS. 4 to 6 involve storing data / information. There are several example options for EIR storage of associations between PEIs and AMF IDs, including: use of an internal data store located within the EIR itself, use of an external entity (e.g., Unstructured Data Storage Function (UDSF)). The implementation of such EIR storage may be subject to network operator discretion. FIG. 7 shows another example signalling and operations diagram between network functions associated with an equipment identity register service according to some example embodiments of the disclosure. In some example embodiments, there are communications between an AMF, and EIR. The EIR may be referred to as an NF / first NF. The AMF may be referred to as a further NF / second NF. In other example embodiments, a mobility management entity (MME) may replace the AMF. At S701, the AMF provides an indication of a PEI to the EIR. The indication may be a request for an equipment status for the PEI. For example, the AMF may provide ‘GET... / equipment-status?pei={pei}’ to the EIR. The EIR determines, based on the PEI, whether there is a record for the PEI that is accessible to the EIR. At S702a, when there is no record for the PEI, the EIR provides an indication to the AMF that the PEI was not found. For example, the EIR may provide ‘404 Not found’ to the AMF. At S702b, when there is a record for the PEI, the EIR accesses the record and determines the associated status (or equipment status) for the PEI. The EIR provides, to the AMF, an indication of the status for the PEI. In some example embodiments, the EIR provides an indication that the PEI is permitted. For example, the EIR may provide ‘OK EirResponseData (“WHITELISTED”)’ to the AMF. At S703, the EIR stores information related to the PEI that was received from the AMF. The EIR may store an association between the AMF and PEI. For example, an identity of the AMF (‘AMF ID’) may be associated with the PEI, and stored at a location accessible to the EIR. At S704, a subscriber associated with the PEI deregisters from the network (e.g., deregisters from the AMF). The AMF manages the deregistration of the subscriber. At S705, the AMF provides, to the EIR, a request to delete the association between the AMF and the PEI. For example, the AMF provides ‘DELETE ... / equipment-status-associations / {pei}’ to the EIR. At S706, the EIR removes (or deletes) the association between the AMF and the PEI. At S707, the EIR provides an acknowledgment to the AMF. The acknowledgement may indicate to the AMF that the association has been deleted. FIG. 8 shows another example signalling and operations diagram between network functions associated with an equipment identity register service according to some example embodiments of the disclosure. In some example embodiments, there are communications between an AMF, and EIR. The EIR may be referred to as an NF / first NF. The AMF may be referred to as a further NF / second NF. In other example embodiments, a mobility management entity (MME) may replace the AMF. At S801, the AMF provides an indication of a PEI to the EIR. The indication may be a subscription request for notifications for the PEI. For example, a subscription to notifications, for the PEI, for any changes in status (equipment status). The subscription request also includes an indication for a current status of the PEI to be provided. For example, a parameter (e.g., ‘immediateReport’ parameter) may be marked as ‘TRUE’ in the subscription request to the EIR. For example, the AMF provides ‘POST ... / equipment-status-subscriptions EquipmentStatusSubscription (pei {pei}, immediateReport {true})’ to the EIR. At S802, the EIR stores information related to the PEI that has been received from the AMF. For example, the EIR creates and stores a subscription, for the AMF, to changes in status associated with the PEI. The creating of the subscription may be performed in response to receiving the subscription request from the AMF. As the indication received from the AMF (in S801) included an indication for a current status of the PEI, the EIR determines whether there is a record for the PEI. At S803a, when there is a record accessible to the EIR for the PEI, the EIR provides an indication of the status for the PEI to the AMF. For example, when the PEI is recorded as ‘permitted’, the EIR provides ‘200 OK EirResponseData (immediateReport {“WHITELISTED”})’ to the AMF. At S803b, when there is no record accessible to the EIR for the PEI, the EIR provides an indication that the status for the PEI is unknown, to the AMF. For example, the EIR provides ‘200 OK EirResponseData (immediateReport {“UNKNOWN”})’ to the AMF. At S804, a subscriber associated with the PEI deregisters from the network (e.g., deregisters from the AMF). The AMF manages the deregistration of the subscriber. At S805, the AMF provides, to the EIR, a request to delete the subscription, for the AMF, to notifications about the PEI. The request may comprise an identifier for the subscription. In some example embodiments, the subscription has an identity (subscription ID). For example, the AMF may provide ‘DELETE ... / equipment-status-subscriptions / {subscriptionlD}’ to the EIR. At S806, the EIR removes (or deletes) the subscription for the AMF. At S807, the EIR provides an acknowledgment to the AMF. The acknowledgement may indicate to the AMF that the subscription has been deleted. FIG. 9 shows another example signalling and operations diagram between network functions associated with an equipment identity register service according to some example embodiments of the disclosure. In some example embodiments, there are communications between an AMF (‘AMF1’), a further AMF (‘AMF2’), and EIR. The EIR may be referred to as an NF / first NF. AMF1 may be referred to as a further NF / second NF. AMF2 may be referred to as a third NF. In other example embodiments, a mobility management entity (MME) may replace AMF1 or AMF2. At S901, AMF1 provides an indication of a PEI to the EIR. The indication may be a request for an equipment status for the PEI. For example, AMF1 may provide ‘GET... / equipment-status?pei={pei}’ to the EIR. The EIR determines, based on the PEI, whether there is a record for the PEI that is accessible to the EIR. At S902a, when there is no record for the PEI, the EIR provides an indication to AMF1 that the PEI was not found. For example, the EIR may provide ‘404 Not found’ to AMF1. At S902b, when there is a record for the PEI, the EIR accesses the record and determines the associated status (or equipment status) for the PEI. The EIR provides, to AMF1, an indication of the status for the PEI. In some example embodiments, the EIR provides an indication that the PEI is permitted. For example, the EIR may provide ‘OK EirResponseData (“WHITELISTED”)’ to AMF1. At S903, the EIR stores information related to the PEI that was received from the AMF1. The EIR may store an association between AMF1 and PEI. For example, an identity of AMF1 (‘AMF ID’) may be associated with the PEI, and stored at a location accessible to the EIR. At S904, a subscriber associated with the PEI registers with a new AMF (i.e., AMF2). In this manner, the subscriber associated with the PEI is moving from AMF1 to AMF2. At S905, AMF2 provides an indication of a PEI to the EIR. The indication may be a request for an equipment status for the PEI. For example, AMF2 may provide ‘GET... / equipment-status?pei={pei}’ to the EIR. At S906, the EIR stores an association between AMF2 and the PEI. The EIR deletes the association between AMF1 and the PEI. In this manner, the receiving of the PEI from AMF2 causes the EIR to replace the stored association between AMF1 and the PEI with an ‘updated’ association between AMF2 and the PEI. At S907, the EIR provides, to AMF2 an indication of the status for the PEI. In some example embodiments, the EIR provides an indication that the PEI is permitted. For example, the EIR may provide ‘OK EirResponseData (“WHITELISTED”)’ to the AMF2. FIG. 10 shows another example signalling and operations diagram between network functions associated with an equipment identity register service according to some example embodiments of the disclosure. In some example embodiments, there are communications between an AMF (‘AMF1’), a further AMF (‘AMF2’), and EIR. The EIR may be referred to as an NF / first NF. AMF1 may be referred to as a further NF / second NF. AMF2 may be referred to as a third NF. In other example embodiments, a mobility management entity (MME) may replace the AMF1 / AMF2. AtS1001, theAMFI provides an indication of a PEI to the EIR. The indication maybe a subscription request for notifications for the PEI. For example, a subscription to notifications, for the PEI, for any changes in status (e.g., equipment status). The subscription request also includes an indication for a current status of the PEI to be provided. For example, a parameter (e.g., ‘immediateReport’ parameter) may be marked as ‘TRUE’ in the subscription request to the EIR. For example, AMF1 provides ‘POST ... / equipment-status-subscriptions EquipmentStatusSubscription (pei {pei}, immediateReport {true})’ to the EIR. At S1002, the EIR stores information related to the PEI that has been received from the AMF1. For example, the EIR creates and stores a subscription, for AMF1, to changes in status associated with the PEI. The creating of the subscription may be performed in response to receiving the subscription request from AMF1. As the indication received from the AMF1 (in S1001) included an indication for a current status of the PEI, the EIR determines whether there is a record for the PEI. At S1003a, when there is a record accessible to the EIR for the PEI, the EIR provides an indication of the status for the PEI to AMF1. For example, when the PEI is recorded as ‘permitted’, the EIR provides ‘200 OK EirResponseData (immediateReport {“WHITELISTED”})’ to AMF1. AtS1003b, when there is no record accessible to the EIR for the PEI, the EIR provides an indication that the status for the PEI is unknown, to AMF1. For example, the EIR provides ‘200 OK EirResponseData (immediateReport {“UNKNOWN”})’ to AMF1. At S1004, a subscriber associated with the PEI registers with a new AMF (i.e., AMF2). In this manner, the subscriber associated with the PEI is moving from AMF1 to AMF2. At S1005, AMF2 provides, to the EIR, an indication of a PEI. The indication may be a subscription request for notifications for the PEI. For example, a subscription to notifications, for the PEI, for any changes in status (equipment status). The subscription request also includes an indication for a current status of the PEI to be provided. For example, a parameter (e.g., ‘immediateReport’ parameter) may be marked as ‘TRUE’ in the subscription request to the EIR. For example, AMF2 provides ‘POST ... / equipment-status-subscriptions EquipmentStatusSubscription (pei {pei}, immediateReport {true})’ to the EIR. At S1006, the EIR creates and stores subscription for AMF2 to notifications about the status of PEI. The EIR deletes the subscription for AMF1 to notification about the status of PEI. In other example embodiments, the EIR updates (or changes) the subscription so that AMF1 is updated to AMF2 for notifications related to the status of the PEI. In this manner, the receiving of the subscription request from AMF2 causes the EIR to replace the subscription for AMF1 with an ‘updated’ subscription for AMF2. At S1007, the EIR provides an indication of the status for the PEI to AMF2. For example, when the PEI is recorded as ‘permitted’, the EIR provides ‘200 OK EirResponseData (immediateReport {“WHITELISTED”})’ to the AMF2. FIG. 11 shows an example signalling and operations diagram between network functions associated with an equipment identity register service according to some example embodiments of the disclosure. In some example embodiments, there are communications between an AMF, EIR, and operations, administration and maintenance (OAM). The EIR may be referred to as an NF / first NF. The AMF may be referred to as a further NF / second NF. In other example embodiments, a mobility management entity (MME) may replace the AMF. In other example embodiments, an NF or other network service may replace the OAM. At S1101, the AMF provides an indication of a PEI to the EIR. The indication may be a request for an equipment status for the PEI. For example, the AMF may provide ‘GET... / equipment-status?pei={pei}’ to the EIR. The EIR determines, based on the PEI, whether there is a record for the PEI that is accessible to the EIR. At S1102, when there is a record for the PEI, the EIR accesses the record and determines the associated status (or equipment status) for the PEI. The EIR provides, to the AMF, an indication of the status for the PEI. In some example embodiments, the EIR provides an indication that the PEI is permitted. For example, the EIR may provide ‘OK EirResponseData (“WHITELISTED”)’ to the AMF. At S1103, the EIR stores information related to the PEI that was received from the AMF. The EIR may store an association between the AMF and PEI. For example, an identity of the AMF (‘AMF ID’) may be associated with the PEI, and stored at a location accessible to the EIR. At S1104, the EIR receives, from OAM, a request to remove the record for the PEI. At S1105, the EIR provides, to the AMF, an indication that the record for the PEI has been deleted at the EIR. At S1106, the EIR deletes the record for the PEI. The EIR keeps the association between the AMF and PEI. Stated differently, the association between the AMF and the PEI is maintained in storage (after the record for the PEI has been deleted). At S1107, the AMF provides, to the EIR, an acknowledgement of the message received in S1105. FIG. 12 shows another example signalling and operations diagram between network functions associated with an equipment identity register service according to some example embodiments of the disclosure. In some example embodiments, there are communications between an AMF, EIR, and OAM. The EIR may be referred to as an NF / first NF. The AMF may be referred to as a further NF / second NF. In other example embodiments, a mobility management entity (MME) may replace the AMF. In other example embodiments, an NF or other network service may replace the OAM. At S1201, the AMF provides an indication of a PEI to the EIR. The indication may be a subscription request for notifications for the PEI. For example, a subscription to notifications, for the PEI, for any changes in status (e.g., equipment status). The subscription request also includes an indication for a current status of the PEI to be provided. For example, a parameter (e.g., ‘immediateReport’ parameter) may be marked as ‘TRUE’ in the subscription request to the EIR. For example, the AMF provides ‘POST ... / equipment-status-subscriptions EquipmentStatusSubscription (pei {pei}, immediateReport {true})’ to the EIR. At S1202, the EIR stores information related to the PEI that has been received from the AMF. For example, the EIR creates and stores a subscription, for the AMF, to changes in status associated with the PEI. The creating of the subscription may be performed in response to receiving the subscription request from the AMF. As the indication received from the AMF (in S1201) included an indication for a current status of the PEI, the EIR determines whether there is a record for the PEI. At S1203, when there is a record accessible to the EIR for the PEI, the EIR provides an indication of the status for the PEI to the AMF. The status of the PEI is stored as part of the record for the PEI. For example, when the PEI is recorded as ‘permitted’, the EIR provides ‘200 OK EirResponseData (immediateReport {“WHITELISTED”})’ to the AMF. At S1204, the EIR receives, from OAM, a request to remove the record for the PEI. The EIR deletes the record for the PEI. At S1205, the EIR provides, to the AMF, an indication related to the status associated with the PEI. The EIR may provide a message / notification indicating the (current) status of the PEI. In some example embodiments, the record for the PEI has been deleted at the EIR. In this manner, the status of the PEI is no longer known. For example, the EIR may provide ‘POST EquipmentStatusChangeNotif ({pei}, “UNKNOWN”)’ or ‘POST EquipmentStatusChangeNotif ({pei}, “STATUS_DELETED”)’ to the AMF. At S1206, the EIR keeps the subscription for the AMF to notifications related to the status of the PEI. Stated differently, the subscription is maintained in storage (even though the record for the PEI has been deleted). At S1207, the AMF provides, to the EIR, an acknowledgement of the message received in S1205. As shown in FIGS. 9 to 12, information related to the PEI (e.g., an association or subscription) may be stored at the EIR, and is continued to be stored even though the record has been deleted. In some example embodiments, an association or subscriptions being stored at the EIR may utilise expiry times (or timers) enabling (or otherwise facilitating) the EIR to remove ‘expired’ subscriptions. For example, each association or subscription has a timer, which when expired, causes the deletion of that association or subscription. Similar mechanisms are used elsewhere in 5GC to clear up subscriptions to notifications. It should be understood that, in FIGS. 4 to 12, one or more of the features may be removed or performed in a different order, in some other example embodiments. One or more of the example embodiments described above have the advantage that communication devices (with an associated PEI) have access to the network for a shorter duration of time following the communication device being marked as blocked. For example, after the communication device has been marked as stolen. One or more of the example embodiments have the advantage that the EIR is able to determine the AMF that is associated with the blocked / prohibited communication device, and provide an indication or notification to the AMF (e.g., directly) of the updated status. The EIR can determine the associated AMF without communicating with a UDM / UDR. Utilising the UDM / UDR increases both the time to determine the AMF associated with the communication device, and uses more resources. Therefore, one or more of the example embodiments provide an enhanced (e.g., quicker and more resource efficient) way to notify an AMF of blocked / prohibited device. The AMF is then able to take the appropriate actions to remove access to the network for the blocked / prohibited device. FIG. 13 shows an example method flow performed by an apparatus according to some example embodiments of the disclosure. The apparatus may be for a network function. The apparatus may provide a network function. A network function may be comprised in the apparatus. The apparatus may be a network function. In some example embodiments, the network function is an EIR. In S1301, the method comprises receiving, from a second network function, an indication of a permanent equipment identifier. In S1303, the method comprises storing information associated with the indication of the permanent equipment identifier received from the second network function. In S1305, the method comprises receiving an indication of a status associated with the permanent equipment identifier. In S1307, the method comprises based on the information, providing, to the second network function, an indication related to the status associated with the permanent equipment identifier. FIG. 14 shows an example method flow performed by an apparatus according to some example embodiments of the disclosure. The apparatus may be for a second network function. The apparatus may provide a second network function. A second network function may be comprised in the apparatus. The apparatus may be a second network function. In some example embodiments, the second network function is an AMF or MME. In S1401, the method comprises providing, to a network function, an indication of a permanent equipment identifier. In S1403, the method comprises receiving, from the network function, an indication related to a status associated with the permanent equipment identifier. FIG. 15 shows a schematic representation of non-volatile memory media 1500a (e.g. Blu-ray disc (BD), computer disc (CD) or digital versatile disc (DVD)) and 1500b (e.g. flash memory, solid state memory, universal serial bus (USB) memory stick) storing instructions and / or parameters 1502 which when executed by a processor allow the processor to perform one or more of the methods (or portions thereof) of FIGS. 13 to 14. It is noted that while various example embodiments are described herein, there are several variations and modifications that may be made to the disclosed solution(s) without departing from the scope of the disclosure. For example, it should be appreciated that further example embodiments may be provided by the combination of any two or more of the various example embodiments described herein. In general, some example embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. For example, some aspects of the various example embodiments may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although embodiments are not limited thereto. While various example embodiments may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as nonlimiting and illustrative examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof. The example embodiments may be implemented by computer software stored in a memory and executable by at least one data processor of the involved entities or by hardware, or by a combination of software and hardware. Further in this regard it should be noted that any procedures may represent program steps, or interconnected logic circuits, blocks and functions, or a combination of program steps and logic circuits, blocks and functions. The software may be stored on such physical media as memory chips, or memory blocks implemented within the processor, magnetic media such as hard disk or floppy disks, and optical media such as for example DVD and the data variants thereof, CD. The term “non-transitory”, as used herein, is a limitation of the medium itself (e.g., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs ROM). As used herein, “at least one of the following:” and “at least one of: ” and similar expressions, where the list of two or more elements are joined by “and”, or “or”, refers to any and all combinations of the listed terms, including at least any one of the elements, or at least any two or more of the elements, or at least all of the elements. As used herein, the expression “and / or” refers to any and all combinations of the listed terms, including any one of the elements, or any two or more of the elements, or at least all of the elements. As used herein, unless stated explicitly to the contrary, performing a step or functionality “in response to A” does not indicate that the step or functionality is performed immediately after “A” occurs as one or more intervening steps may be included therebetween. Analogously, performing a step or functionality “based on A” does not indicate that the step or functionality is performed solely based on “A” as the step or functionality may be further based on one or more additional conditions (such as “B”) in addition to “A”. The memory may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The data processors may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASIC), gate level circuits and processors based on multi core processor architecture, as nonlimiting examples. As used herein, the term “means for”, or “means configured to perform” (or similar) may be any means that are suitable for performing the feature. The “means” may be configured to perform one or more of the functions and / or method steps previously described. For example, the “means” may include one or more of: at least one processor, at least one memory, transceiver circuitry, antenna circuitry, etc. It should be understood that these are provided as non-limiting examples. Additionally or alternatively, some examples may be implemented using circuitry. The circuitry may be configured to perform one or more of the functions and / or method steps previously described. That circuitry may be provided in the base station and / or in the communications device. As used herein, the term “circuitry” may refer to one or more or all of the following example embodiments: (a) hardware-only circuit implementations (such as implementations in only analogue and / or digital circuitry); (b) combinations of hardware circuits and software, such as: (i) a combination of analogue and / or digital hardware circuit(s) with software / firmware and (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as the communications device or base station to perform the various functions previously described; and (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation. This definition of circuitry applies to uses of the term “means” herein, including in any claims. As a further example, as used herein, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example integrated device. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in a server, a cellular network device, or other computing or network device. The foregoing description has provided, by way of illustrative and non-limiting example, a full and informative description of the various example embodiments of this disclosure. However, various modifications and adaptations may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings and the claims. However, all such and similar modifications of the teachings will still fall within the scope as defined in the disclosure.

Claims

1. An apparatus comprising means for:receiving, from a second network function, an indication of a permanent equipment identifier;storing information associated with the indication of the permanent equipment identifier received from the second network function;receiving an indication of a status associated with the permanent equipment identifier; andbased on the information, providing, to the second network function, an indication related to the status associated with the permanent equipment identifier.

2. The apparatus according to claim 1, wherein the indication of the status associated with the permanent equipment identifier is an indication that the status has changed to a status indicating that the permanent equipment identifier is prohibited.

3. The apparatus according to claim 1 or claim 2 , wherein the means are further for: based on the indication of the status that has been received, generating or updating a record associated with the permanent equipment identifier, the record for the permanent equipment identifier including the status of the permanent equipment identifier.

4. The apparatus according to any of claims 1 to 3, wherein the storing of the information comprises:storing, based on the indication of the permanent equipment identifier, an association between the second network function and the permanent equipment identifier,wherein the indication related to the status associated with the permanent equipment identifier provided to the second network function is based on the association.

5. The apparatus according to any of claims 1 to 4, wherein the indication related to the status associated with the permanent equipment identifier comprises:a request for the second network function to deregister a subscriber associated with the permanent equipment identifier.

6. The apparatus according to any of clams 1 to 5, wherein the storing of the information comprises:storing, based on the indication of the permanent equipment identifier, a subscription, for the second network function, to changes in status associated with the permanent equipment identifier,wherein the indication related to the status associated with the permanent equipment identifier being provided to the second network function is based on the subscription.

7. The apparatus according to any of claims 1 to 6, wherein the indication related to the status associated with the permanent equipment identifier comprises:an indication that the status associated with the permanent equipment identifier has changed, and an indication of the status associated with the permanent equipment identifier.

8. The apparatus according to any of claims 1 to 7, wherein the indication of the permanent equipment identifier is received in a request for a status associated with the permanent equipment identifier.

9. The apparatus according to any of claims 1 to 8, wherein the indication of the permanent equipment identifier is received in a request for subscription to notifications related to the status associated with the permanent equipment identifier.

10. The apparatus according to any of claims 1 to 9, wherein the means are further for: in response to receiving the request for subscription to a status associated with the permanent equipment identifier, providing, to the second network function, one of: the status associated with the permanent equipment identifier from the record for the permanent equipment identifier, or an indication that there is no stored record available for the permanent equipment identifier.

11. The apparatus according to any of claims 1 to 10, wherein the indication of the status associated with the permanent equipment identifier is received from an operations, administration and maintenance service.

12. The apparatus according to any of claims 1 to 11, wherein the means for further for: deleting the information associated with the indication of the permanent equipment identifier received from the second network function based on one of:a request to delete the information being received from the second network function; oran indication of the permanent equipment identifier being received from a third network function.

13. An apparatus comprising means for:providing, to a network function, an indication of a permanent equipment identifier; and receiving, from the network function, an indication related to a status associated with the permanent equipment identifier.

14. The apparatus according to claim 13, wherein the indication related to a status associated with the permanent equipment identifier received from the network function comprises: a request for the second network function to deregister a subscriber associated with the permanent equipment identifier.

15. The apparatus according to claim 13 or claim 14, wherein the indication related to a status associated with the permanent equipment identifier received from the network function comprises:an indication that the status associated with the permanent equipment identifier has changed, and an indication of the status associated with the permanent equipment identifier.

16. The apparatus according to any of claims 13 to 15, wherein the indication related to a status associated with the permanent equipment identifier received from the network function comprises: an indication that the status has changed to a status indicating that the permanent equipment identifier is prohibited.

17. The apparatus according to any of claims 13 to 16, wherein the providing, to a network function, an indication of a permanent equipment identifier comprises:providing, to the network function, a request for subscription to notifications related to the status associated with the permanent equipment identifier.

18. The apparatus according to any of claims 13 to 17, wherein the request comprises: an indication for the status of the permanent equipment identifier that is currently stored to be provided.

19. The apparatus according to any of claims 13 to 18, wherein the means are further for: based on the request, receiving, from the network function, one of: the status associated with the permanent equipment identifier from a record for the permanent equipment identifier, or an indication that there is no stored record available for the permanent equipment identifier.

20. The apparatus according to any of claims 13 to 19, wherein the means are further for: providing, to the network function, a request to delete information that is stored at the network function related to the second network function and the permanent equipment identifier.

21. The apparatus according to any of the preceding claims, wherein the at least one of the following: the network function is an equipment identity register, the second network function is an access and mobility management function, the second network function is a mobility management entity, the third network function is a further access and mobility management function, or the third network function is a further mobility management entity.

22. A method comprising:receiving, from a second network function, an indication of a permanent equipment identifier;storing information associated with the indication of the permanent equipment identifier received from the second network function;receiving an indication of a status associated with the permanent equipment identifier; andbased on the information, providing, to the second network function, an indication related to the status associated with the permanent equipment identifier.

23. A method comprising:providing, to a network function, an indication of a permanent equipment identifier; and receiving, from the network function, an indication related to a status associated with the permanent equipment identifier.

24. A computer program comprising instructions, which when executed by an apparatus, cause the apparatus to perform at least the following:receiving, from a second network function, an indication of a permanent equipment identifier;storing information associated with the indication of the permanent equipment identifier received from the second network function;receiving an indication of a status associated with the permanent equipment identifier; andbased on the information, providing, to the second network function, an indication related to the status associated with the permanent equipment identifier.

25. A computer program comprising instructions, which when executed by an apparatus, cause the apparatus to perform at least the following:providing, to a network function, an indication of a permanent equipment identifier; and receiving, from the network function, an indication related to a status associated with5 the permanent equipment identifier.

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