Method and apparatus for buffering real-time transport protocol packets

Abstract

The present disclosure provides methods for buffering Real-time Transport Protocol, RTP, packets by a Default Bearer Media Handler Function, DBMHF, device (302). A method performed by a DBMHF device (302) includes receiving (306), from a Bearer Binding Intercept and Forward Function, BBIFF, device (112), Internet Protocol, IP, Multimedia Subsystem, IMS, traffic on a default bearer and determining (308) that the IMS traffic comprises an RTP packet. The method further includes buffering (310) the RTP packet and receiving (320), from the BBIFF device, an instruction to forward the RTP packet to an LI Mirror IMS State Function, LMISF, (114) wherein the instruction comprises an associated dedicated bearer identity. The method further includes forwarding (322) the RTP packet to the LMISF (114) with the associated dedicated bearer identity.

Description

[0001] METHOD AND APPARATUS FOR BUFFERING REAL-TIME TRANSPORT PROTOCOL

[0002] PACKETS

[0003] TECHNICAL FIELD

[0004] The disclosure relates to methods for buffering Real-time Transport Protocol (RTP) packets by a Default Bearer Media Handler Function (DBMHF). This disclosure also relates to network nodes configured to perform the same as well as a corresponding computer program and a carrier.

[0005] BACKGROUND

[0006] Figure 1 shows an example of an S8 Home Routing (S8HR) roaming architecture as defined in Third Generation Partnership Program (3GPP) Technical Specification (TS) 33.107 V17.0.0 (2022-04).

[0007] The S8HR roaming architecture is used for Voice over Long Term Evolution (VoLTE) calls where the Packet Data Network (PDN) Gateway (PDN-GW) 106 and the Proxy Call Session Control Function (P-CSCF) 108 are located in the Home Public Land Mobile Network (HPLMN) 104 while the Serving Gateway (S-GW) 110 is located in the Visited PLMN (VPLMN) 102. The User Equipment (UE) Internet Protocol (IP) Multimedia Subsystem (IMS) signaling and the media packets are routed directly to the HPLMN 104 through an S8 reference point 120 between the S-GW 110 and the PDN-GW 106.

[0008] The IMS signaling messages are exchanged between the UE 118 and the P-CSCF 108 (in HPLMN 104 with S8HR) and the media is exchanged between the UE 118 and the PDN-GW 106 (in HPLMN 104 with S8HR). Within the VPLMN 102 with S8HR, the IMS signaling messages are carried over the General Packet Radio Service (GPRS) Tunneling Protocol (GTP) tunnel that corresponds to the IMS Signaling Bearer and the media packets are carried over the GTP tunnel that corresponds to the Media Bearer, (i.e.: a dedicated Evolved Packet System (EPS) Bearer used to carry the media packets).

[0009] In the standardized solution it is assumed that the EPS Bearer ID of the IMS Signaling Bearer is always linked to the dedicated EPS Bearer used as a Media Bearer.

[0010] In the VPLMN 102 there is no IMS node, so the interception of the VoLTE inbound roaming subscribers' traffic is only possible in the nodes of the EPS domain.

[0011] However, in the EPS there is no Session Initiation Protocol (SIP) handling, so by intercepting in that domain there is no possibility to retrieve the information about SIP identities and about both the IMS signaling and the payload, which poses a severe limitation to the effectiveness of the interception of VoLTE calls for inbounding roamers.

[0012] To overcome this limitation, Third Generation Partnership Program (3GPP) has specified the Lawful Interception (LI) architecture and functions for S8HR, introducing in the network the following two new functional entities, that make it possible to intercept the VoLTE calls to / from inbound roamers in the Evolved Packet Core (EPC) nodes, providing IMS-like interception. The first is LI Mirror IMS State Function (LMISF) 114 which mirrors the home network's Session Border Gateway (SBG) functionality. It keeps a list of the IMS targets, generates "IMS-like" Intercept Related Information (IRI), triggers the Content of Communication (CC) interception for those VoLTE inbound roamers' communications related to the intercepted targets and sends them to the LI Mediation Function.

[0013] The second function is the Bearer Binding Intercept and Forwarding Function (BBIFF) 112 which is a functionality in the S-GW 110 in the EPC network. It recognizes the IMS signaling packets related to the VoLTE inbound roamers' communications, captures the IMS media packets related to the intercepted targets and forwards them to the LMISF.

[0014] These Li-specific functions are introduced to examine the packets that flow through the VPLMN packet core network nodes (i.e.: S-GW) to generate IRI and CC when the communication involves an inbound roaming target. The LI architecture diagram shown in Figure 2 is redrawn below with focus on the new LI specific functions and the reference points.

[0015] A prerequisite for the operation of S8HR LI is that the IMS signaling messages and the media packets are not encrypted at S-GW / BBIFF. This shall be set in the HPLMN. Furthermore, the S8HR LI solution requires that Access Point Names (APNs) are identified as being used for S8HR and therefore those APNs are used to identify the EPS Bearers used for inbound roamers with S8HR.

[0016] Li-specific reference points include Xia which is the reference point between S- GW / BBIFF and LMISF. This reference point is used to carry the user plane information from the S-GW 110 / BBIFF device 112 to the LMISF 114. The Xib reference point is between the LMISF and the S-GW / BBIFF. This reference point is used to exchange the control plane information between the LMISF 114 and the S-GW 110 / BBIFF device 112. In an embodiment, BBIFF device 112 is a LI specific function introduced to support the lawful interception of voice services in the VPLMN 102 when S8HR is used as the roaming architecture. Some of the following functions performed by the BBIFF device 112 include:

[0017] • Receive a list of S8HR APNs and the packet forwarding rules that apply to all users from the LMISF 114 over the Xib reference point.

[0018] • As per the LMISF 114 instruction, notify the LMISF 114 over Xib reference point whenever the IMS Signaling Bearer or the Media Bearer with S8HR APN is created, modified or deleted. In that notification, the UE location information received from the MME shall be included.

[0019] • As per the packet forwarding rules (i.e. as instructed by the LMISF), deliver the packets of all GTP tunnels used for IMS Signaling Bearer with S8HR APN to the LMISF 114 over the Xia reference point.

[0020] • Receive the intercepted IMS Signaling Bearer information from the LMISF 114 over the Xib reference point along with the packet forwarding rules.

[0021] • Identify the dedicated EPS Bearer used as the Media Bearer linked to the above-indicated intercepted IMS Signaling Bearer.

[0022] • As per the packet forwarding rules (i.e. as instructed by the LMISF 114), deliver the packets of the GTP tunnel used for Media Bearer associated with the intercepted IMS Signaling Bearer to the LMISF 114 over the Xia reference point.

[0023] • When instructed by the LMISF 114, stop delivering the packets of the GTP tunnels used for Media Bearers associated with the IMS Signaling Bearer with a deactivated interception.

[0024] The LMISF 114 is a LI specific function introduced to support the lawful interception of voice services in the VPLMN when S8HR is used as the roaming architecture. Some of the functions performed by the LMISF include:

[0025] • Provide S8HR APN information to the S-GW 110 / BBIFF device 112 over the Xib reference point.

[0026] • Instruct S-GW 110 / BBIFF device 112 over Xib reference point to notify (to LMISF 114) whenever an IMS Signaling Bearer or a Media Bearer with S8HR APN is created, modified or deleted. • Instruct S-GW 110 / BBIFF device 112 over the Xib reference point to start delivering the packets (to LMISF 114) of all IMS Signaling Bearers with S8HR APN.

[0027] • Receive target identity information from the ADMF over the Xl_l reference point.

[0028] • Receive the notification from S-GW 110 / BBIFF device 112 over the Xib reference point whenever an IMS Signaling Bearer or a Media Bearer with S8HR APN is created, modified or deleted.

[0029] • Store the IMS Signaling Bearer information (e.g. EPS Bearer ID) along with the IMSI associated with the UE to which the IMS Signaling Bearer was created, modified or deleted. Store or update the most recent UE location information received along with the IMS Signaling Bearer or the Media Bearer information.

[0030] • Receive and examine the IMS signaling messages delivered by the S-GW 110 / BBIFF device 112 over the Xia reference point.

[0031] • Receive media packets delivered by the S-GW 110 / BBIFF device 112 over the Xia reference point. Identify the intercepted IMS session that relates to the media packets.

[0032] • Maintain an IMS signaling state for all inbound roamers with S8HR that are registered to the network or in an IMS session. Part of this function is to track all IMS registrations, re-registrations and de-registrations of inbound roamers with S8HR.

[0033] • After examining and determining that the IMS signaling messages involves a target, establish and maintain a map between the target identity and the IMS Signaling Bearer information or the Media Bearer (e.g. EPS Bearer ID along with the International Mobile Subscriber Identity (IMSI) value of the UE). When the IMS signaling messages do not involve a target, establish and maintain a map between the IMS Signaling Bearer or the Media Bearer information and the potential target identities.

[0034] • Generate and deliver the IRI to the Mediation and Delivery Function 2 (MDF2) 202.

[0035] • Inform the S-GW 110 / BBIFF device 112 over the Xib reference point with the IMS Signaling Bearer information associated with an intercepted IMS session that requires CC interception and instruct the S-GW 110 / BBIFF device 112 to start delivering the packets of the Media Bearer associated with that IMS Signaling Bearer.

[0036] • Inform the S-GW 110 / BBIFF device 112 over the Xib reference point with the IMS Signaling Bearer information associated with a deactivated interception and instruct the S-GW 110 / BBIFF device 112 to stop delivering the packets of the Media Bearer associated with that IMS Signaling Bearer. Generate and deliver the IRI messages to the MDF2 202.

[0037] • Generate and deliver the CC to the MDF3 204.

[0038] • When target identity is received from the ADMF, determine whether any IMS Signaling Bearer is associated to the target identity. If yes, start the interception process.

[0039] • Provide the decompression of IMS signaling messages upon detecting the compression.

[0040] SUMMARY

[0041] An object of the invention is to improve Lawful Interception (LI) in an S8 Home Routing (S8HR) roaming communication session at the visited network.

[0042] The present disclosure provides methods for buffering Real-time Transport Protocol (RTP) packets by a Default Bearer Media Handler Function (DBMHF) device. A method performed by a DBMHF device includes receiving, from a Bearer Binding Intercept and Forward Function (BBIFF) device, Internet Protocol (IP) Multimedia Subsystem (IMS) traffic on a default bearer and determining that the IMS traffic comprises an RTP packet. The method further includes buffering the RTP packet and receiving, from the BBIFF device, an instruction to forward the RTP packet to an LI Mirror IMS State Function (LMISF) wherein the instruction comprises an associated dedicated bearer identity. The method further includes forwarding the RTP packet to the LMISF with the associated dedicated bearer identity.

[0043] In an embodiment, the IMS traffic comprises signaling packets and the method further includes forwarding the signaling packets to the LMISF.

[0044] In an embodiment, the IMS traffic received from the BBIFF device comprises a User Equipment (UE) subscriber identity, and wherein the RTP packet that is buffered is associated with the UE subscriber identity, and the RTP packet is forwarded to the LMISF with the UE subscriber identity.

[0045] In an embodiment, the UE subscriber identity is an International Mobile Subscriber Identity (IMSI).

[0046] In an embodiment, the instruction to forward the RTP packet comprises the UE subscriber identity that identifies the RTP packet.

[0047] In an embodiment, the DBMHF device is associated with an S8HR roaming architecture.

[0048] In an embodiment, the RTP packets are buffered at a temporary UE subscriber identity database.

[0049] In an embodiment, the instruction to forward the RTP packet is concurrent with activation of a dedicated bearer associated with the dedicated bearer identity.

[0050] In an embodiment, a network node is provided that implements the DBMHF device for buffering RTP packets. The network node includes processing circuitry configured to cause the network node to receive, from a BBIFF device, IMS traffic on a default bearer and determine that the IMS traffic comprises an RTP packet. The processing circuitry also causes the network node to buffer the RTP packet and receive, from the BBIFF device, an instruction to forward the RTP packet to an LMISF wherein the instruction comprises an associated dedicated bearer identity. The processing circuitry also causes the network node to forward the RTP packet to the LMISF with the associated dedicated bearer identity.

[0051] In an embodiment, a method for buffering RTP packets is performed by a BBIFF device, where the method includes providing to a DBMHF device IMS traffic on a default bearer where the IMS traffic includes an RTP packet. The method also includes providing to an LMISF a dedicated bearer activation associated with a dedicated bearer and receive from the LMISF a request to send media on the dedicated bearer. The method also includes providing, to the DBMHF device, a request to send the RTP packet to the LMISF, wherein the request to send the RTP packet comprises a dedicated bearer ID associated with the dedicated bearer.

[0052] In an embodiment, the dedicated bearer activation provided to the LMISF comprises a UE subscriber identity, and the request to send the RTP packet to the LMISF comprises the UE subscriber identity.

[0053] In an embodiment, the UE subscriber identity is an IMSI. In an embodiment, the method further includes providing, to the LMISF, media associated with the request to send media on the dedicated bearer.

[0054] In an embodiment, the providing media is concurrent with providing, to the DBM HF device, the request to send the RTP packet to the LMISF.

[0055] In an embodiment, a network node that implements a BBIFF device for buffering RTP packets is provided where the network node includes processing circuitry configured to cause the network node to provide to a DBMHF device IMS traffic on a default bearer where the IMS traffic includes an RTP packet. The processing circuitry also causes the network node to provide to an LMISF a dedicated bearer activation associated with a dedicated bearer and receive from the LMISF a request to send media on the dedicated bearer. The processing circuitry also causes the network node to provide, to the DBMHF device, a request to send the RTP packet to the LMISF, wherein the request to send the RTP packet comprises a dedicated bearer ID associated with the dedicated bearer.

[0056] In an embodiment, a computer program includes instructions which, when executed on processing circuitry, causes the processing circuitry to carry out the methods of any of the embodiments above.

[0057] In an embodiment, a carrier is provided that contains the computer program described above, wherein the carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium.

[0058] In an embodiment, an advantage provided by the methods disclosed herein, is that by buffering the RTP packets and then providing the buffered RTP packets with an indication of the dedicated bearer ID to the LMISF, an initial portion of a communication session can be captured.

[0059] BRIEF DESCRIPTION OF DRAWINGS

[0060] The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the disclosure, and together with the description serve to explain the principles of the disclosure.

[0061] Figure 1 is a schematic block diagram of a S8 Home Routing Architecture according to some embodiments of the present disclosure;

[0062] Figure 2 is a schematic block diagram of a Lawful Interception (LI) Mirror Internet Protocol (IP) Multimedia Subsystem (IMS) State Function (LMISF) and Bearer Binding Intercept and Forward Function (BBIFF) device interworking and reference points according to some embodiments of the present disclosure;

[0063] Figure 3 is a message sequence chart of a method for buffering Real-time Transport Protocol (RTP) packets according to some embodiments of the present disclosure;

[0064] Figure 4 is a schematic block diagram of a network node according to some embodiments of the present disclosure;

[0065] Figure 5 is a schematic block diagram that illustrates a virtualized embodiment of the network node of Figure 4 according to some embodiments of the present disclosure; and

[0066] Figure 6 is a schematic block diagram of the network node of Figure 4 according to some other embodiments of the present disclosure.

[0067] DETAILED DESCRIPTION

[0068] The embodiments set forth below represent information to enable those skilled in the art to practice the embodiments and illustrate the best mode of practicing the embodiments. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure.

[0069] Network Node: As used herein, a "network node" can be any type of apparatus / device in a core network or any apparatus / device that implements a core network function. Some examples of a core network node include a computer or server host for e.g., a Mobility Management Entity (MME), a Packet Data Network Gateway (P- GW), a Service Capability Exposure Function (SCEF), a Home Subscriber Server (HSS), or the like. Some other examples of a core network node include a node implementing an Access and Mobility Management Function (AMF), a User Plane Function (UPF), a Session Management Function (SMF), an Authentication Server Function (AUSF), a Network Slice Selection Function (NSSF), a Network Exposure Function (NEF), a Network Function (NF) Repository Function (NRF), a Policy Control Function (PCF), a Unified Data Management (UDM), or the like. In the following description, when stating that any of these functions, such as a Default Bearer Media Handler Function (DBMHF) device or a Bearer Binding Intercept and Forward Function (BBIFF) device, perform an action, such as receiving / matching / performing / configuring then it is to be understood that it is in practice the network node / computer / server host / DBMHF device / BBIFF device that hosts the DBM HF or BBIFF, respectively, that performs the action.

[0070] Note that the description given herein focuses on a 3GPP cellular communications system and, as such, 3GPP terminology or terminology similar to 3GPP terminology is oftentimes used. However, the concepts disclosed herein are not limited to a 3GPP system.

[0071] Global System for Mobile Communications (GSM) Association (GSMA) and Third Generation Partnership Program (3GPP) standards assume that the default Evolved Packet System (EPS) Bearer carries only Internet Protocol (IP) Multimedia Subsystem (IMS) Signaling of the inbound roamers. In some cases, the default EPS Bearer is used for Real-time Transport Protocol (RTP) packets. In an example, the Voice over Long Term Evolution (VoLTE) operator may configure the network to use the default EPS Bearer to transport the initial (e.g.: 2-3 second) of media call to speed up the call setup without waiting for the dedicated EPS Bearer cases. In another example, when the dedicated bearer setup is delayed for any temporary unavailability in the home network involved functions, then the IMS media might be sent via default bearer for all the inbound roaming until the issue is recovered. In each of these examples, the number of ingress packets received in the Lawful Interception (LI) Mirror IMS State Function (LMISF) is much higher than expected. This can lead to system overload and possible LI service outage. Additionally, the initial part of the conversation involved a target is lost.

[0072] The present disclosure provides methods for buffering RTP packets by a DBM HF which solves these identified issues. The DBMHF is provided in the LI architecture in the Visited Public Land Mobile Network (VPLMN) for S8 Home Routing (S8HR) Roaming for the handling of the handling of RTP packets conveyed on the default bearer in the initial phase of the communication session.

[0073] The present disclosure provides methods for buffering Real-time Transport Protocol (RTP) packets by a DBMHF device. A method performed by a DBMHF device includes receiving, from a BBIFF device, Internet Protocol (IP) Multimedia Subsystem (IMS) traffic on a default bearer and determining that the IMS traffic comprises an RTP packet. The method further includes buffering the RTP packet and receiving, from the BBIFF device, an instruction to forward the RTP packet to an LI Mirror IMS State Function (LMISF) wherein the instruction comprises an associated dedicated bearer identity. The method further includes forwarding the RTP packet to the LMISF with the associated dedicated bearer identity.

[0074] In an embodiment, an advantage provided by the methods disclosed herein, is that by buffering the RTP packets and then providing the buffered RTP packets with an indication of the dedicated bearer ID to the LMISF, an initial portion of a communication session can be captured.

[0075] Figure 3 is a message sequence chart of a method for buffering Real-time Transport Protocol (RTP) packets according to some embodiments of the present disclosure.

[0076] Figure 3 introduces a DBM HF device 302 with the scope to deal with RTP packets conveyed on the default EPS bearer in the initial phase of the call media setup and the "International Mobile Subscriber Identity (IMSI) Temporary Buffer" with the scope to buffer the RTP packets of the default bearer with the associated IMSI.

[0077] The DBM HF device 302 is part of the LI architecture that can receive RTP packets from the BBIFF device 112 from the default bearer, buffer the received RTP packets together with an IMSI and send media for the specific IMSI with the specified bearer identification to the LMISF 114 via Xia, when instructed by the LMISF 114.

[0078] At step 306, the BBIFF device 112 can send to the DBMHF device 302, IMS traffic that is on a default bearer, and has a default bearer ID. The IMS traffic is sent to the DBMHF device 302 via the Xia reference point. The Xia reference point is generally used to carry the user plane information from the S-GW 110 / BBIFF device 112 to the LMISF 114, and thus, functionally and logically, the DBMHF device 302 is between the BBIFF device 112 and the LMISF 114. The IMS traffic includes signaling packets, but also in an embodiment, includes RTP packets that contain an initial part of a conversation or communication session.

[0079] At step 308, the DBMHF device 302 determines that IMS traffic includes at least one RTP packet, and in response to identifying the one or more RTP packets, the DBMHF device 302 at step 310 buffers the RTP packets in a temporary UE subscriber identity database 304. The DBMHF device 302 buffers the RTP packets in the temporary UE subscriber identity database 304 with an indication of the default bearer ID and an IMSI associated with the target UE. The DBMHF device 302 will also optionally forward the signaling packets at step 312 to the LMISF 114 to facilitate the establishment of the communication session and a dedicated bearer activation.

[0080] At step 314, the BBIFF device 112 provides to the LMISF 114 p, via the Xib reference point, a dedicated bearer activation that includes a dedicated bearer ID.

[0081] At step 316, the LMISF 114 sends to the BBIFF device 112 via the Xib reference point, a request to send media on the dedicated bearer.

[0082] At step 318, the BBIFF device 112, after receiving the request in step 316, sends the media content to the LMISF 114 via the Xia reference point. The BBIFF device 112 will send the media content that is associated with the dedicated bearer ID on the dedicated bearer. Additionally, at step 320, the BBIFF device 112 sends to the DBMHF device 302 an instruction to forward the buffered RTP packet(s) to the LMISF 114. The instruction can also include an indication of the dedicated bearer ID, and the IMSI that is associated with the media to be sent to the LMISF 114. In an embodiment, the step 318 is performed concurrently with step 320, and in other embodiments, the step 318 precedes step 320, while in other embodiments step 320 precedes step 318.

[0083] At step 322, the DBMHF device 302 retrieves from the temporary UE subscriber identity database 304 the one or more buffered RTP packets and forwards the one or more RTP packets to the LMISF 114. The DBMHF device 302 can include the dedicated bearer ID and optionally the IMSI with the buffered RTP packets to be sent to the LMISF 114. The buffered RTP packets are sent in step 322 via the Xia reference point.

[0084] In an embodiment, for each dedicated bearer ID the LMISF 114 will not receive the RTP packets in the same order as they are originally intercepted in the SIP session from the establishment until the release. An LEMF that receives the LI data uses the time stamps associated with the RTP packets to place the audio / video in the correct timing order. In some embodiments the sequence number of the RTP packets can also be used to order the media. In other embodiments, the sequence number can be used to determine whether any packets have been lost.

[0085] Figure 4 is a schematic block diagram of a network node 400 according to some embodiments of the present disclosure. Optional features are represented by dashed boxes. The network node 400 may be, for example, a network node that implements all or part of the functionality of the DBMHF device 302 or the BBIFF device 112 as described herein and may in the future thus be a network node according to any future telecommunication network standard, such as the emerging 3GPP 6thGeneration network. As illustrated, the network node 400 includes a control system 402 that includes one or more processors 404 (e.g., Central Processing Units (CPUs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), and / or the like), memory / computer readable storage medium 406, and a network interface 408. The one or more processors 404 are also referred to herein as processing circuitry.

[0086] The one or more processors 404 operate to provide one or more functions of a network node 400 as described herein. In some embodiments, the function(s) are implemented in one or more computer programs 410 that are stored, e.g., in the computer readable storage medium 406 and executed by the one or more processors 404. Thus, in one embodiment, the computer program comprises instructions which when executed by the processing circuitry 404 of the DBMHF device 302, causes the DBMHF device 302 to perform the actions attributed to the DBMHF device in conjunction with Figure 3. In another embodiment the computer program comprises instructions which when executed by the processing circuitry 404 of the BBIFF device 302, causes the DBMHF device to perform the actions attributed to the BBIFF device in conjunction with Figure 3.

[0087] Figure 5 is a schematic block diagram that illustrates a virtualized embodiment of the network node 400 according to some embodiments of the present disclosure. This discussion is equally applicable to other types of network nodes. Further, other types of network nodes may have similar virtualized architectures. Again, optional features are represented by dashed boxes.

[0088] As used herein, a "virtualized" network node is an implementation of the network node 400 in which at least a portion of the functionality of the network node 400 is implemented as a virtual component(s) (e.g., via a virtual machine(s) executing on a physical processing node(s) in a network(s)). As illustrated, in this example, the network node 400 may include the control system 402 as described above. The network node 400 includes one or more processing nodes 500 coupled to or included as part of a network(s) 502. If present, the control system 402 is connected to the processing node(s) 500 via the network 502. Each processing node 500 includes one or more processors 504 (e.g., CPUs, ASICs, FPGAs, and / or the like), memory / computer readable storage medium 506, and a network interface 508. In this example, functions 510 of the network node 400 described herein are implemented at the one or more processing nodes 500 or distributed across the one or more processing nodes 500 and the control system 402 in any desired manner. In some particular embodiments, some or all of the functions 510 of the network node 400 described herein are implemented as virtual components executed by one or more virtual machines implemented in a virtual environment(s) hosted by the processing node(s) 500. As will be appreciated by one of ordinary skill in the art, additional signaling or communication between the processing node(s) 500 and the control system 402 is used in order to carry out at least some of the desired functions 510. Notably, in some embodiments, the control system 402 may not be included.

[0089] In some embodiments, a computer program including instructions which, when executed by at least one processor, causes the at least one processor to carry out the functionality of network node 400 or a node (e.g., a processing node 500) implementing one or more of the functions 510 of the network node 400 in a virtual environment according to any of the embodiments described herein is provided. In some embodiments, a carrier comprising the aforementioned computer program product is provided. The carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium (e.g., a non-transitory computer readable medium such as memory).

[0090] Figure 6 is a schematic block diagram of the network node 400 according to some other embodiments of the present disclosure. The network node 400 may include one or more modules DBMHF device 302 or the BBIFF device 112, each of which is implemented in software. The modules DBMHF device 302 or the BBIFF device 112 provide the functionality of the network node 400 described herein. It is to be appreciated that for the purposes of Figure 6, the network node 400 is shown as including both DBMHF device 302, and BBIFF device 112, this is for simplicity of representation, and in other embodiments, the DBMHF device 302 and BBIFF device 112 can be implemented by different network nodes. This discussion is equally applicable to the processing node 500 of Figure 5 where the modules DBMHF device 302 or the BBIFF device 112 may be implemented at one of the processing nodes 500 or distributed across multiple processing nodes 500 and / or distributed across the processing node(s) 500 and the control system 402. Any appropriate steps, methods, features, functions, or benefits disclosed herein may be performed through one or more functional units or modules of one or more virtual apparatuses. Each virtual apparatus may comprise a number of these functional units. These functional units may be implemented via processing circuitry, which may include one or more microprocessor or microcontrollers, as well as other digital hardware, which may include Digital Signal Processors (DSPs), special-purpose digital logic, and the like. The processing circuitry may be configured to execute program code stored in memory, which may include one or several types of memory such as Read Only Memory (ROM), Random Access Memory (RAM), cache memory, flash memory devices, optical storage devices, etc. Program code stored in memory includes program instructions for executing one or more telecommunications and / or data communications protocols as well as instructions for carrying out one or more of the techniques described herein. In some implementations, the processing circuitry may be used to cause the respective functional unit to perform corresponding functions according to one or more embodiments of the present disclosure.

[0091] While processes in the figures may show a particular order of operations performed by certain embodiments of the present disclosure, it should be understood that such order is exemplary (e.g., alternative embodiments may perform the operations in a different order, combine certain operations, overlap certain operations, etc.).

[0092] Those skilled in the art will recognize improvements and modifications to the embodiments of the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein.

Claims

CLAIMS1. A method for buffering Real-time Transport Protocol, RTP, packets performed by a Default Bearer Media Handler Function, DBM HF, device (302), the method comprising: receiving (306), from a Bearer Binding Intercept and Forward Function, BBIFF, device (112), Internet Protocol, IP, Multimedia Subsystem, IMS, traffic on a default bearer; determining (308) that the IMS traffic comprises an RTP packet; buffering (310) the RTP packet; receiving (320), from the BBIFF device (112), an instruction to forward the RTP packet to a Lawful Interception (LI) Mirror IMS State Function, LMISF, (114) wherein the instruction comprises an associated dedicated bearer identity; and forwarding (322) the RTP packet to the LMISF (114) with the associated dedicated bearer identity.

2. The method of claim 1, wherein the IMS traffic comprises signaling packets, and the method further comprises: forwarding (312) the signaling packets to the LMISF (114).

3. The method of any one of claims 1 to 2, wherein the IMS traffic received from the BBIFF device (112) comprises a User Equipment, UE, subscriber identity, and wherein the RTP packet that is buffered is associated with the UE subscriber identity, and the RTP packet is forwarded to the LMISF (114) with the UE subscriber identity.

4. The method of claim 3, wherein the UE subscriber identity is an International Mobile Subscriber Identity, IMSI.

5. The method of any one of claims 3 to 4, wherein the instruction to forward the RTP packet comprises the UE subscriber identity that identifies the RTP packet.

6. The method of any one of claims 1 to 5, wherein the DBM HF device (302) is associated with an S8 Home Routing, S8HR, roaming architecture.

7. The method of any one of claims 1 to 6, wherein the RTP packets are buffered at a temporary UE subscriber identity database (304).

8. The method of any one of claims 1 to 7, wherein the instruction to forward the RTP packet is concurrent with activation of a dedicated bearer associated with the dedicated bearer identity.

9. A network node (400) that implements a Default Bearer Media Handler Function, DBMHF, device (302) for buffering Real-time Transport Protocol, RTP, packets, the network node (400) comprising processing circuitry (404) configured to cause the network node (400) to: receive (306), from a Bearer Binding Intercept and Forward Function, BBIFF, device (112), Internet Protocol, IP, Multimedia Subsystem, IMS, traffic on a default bearer; determine (308) that the IMS traffic comprises an RTP packet; buffer (310) the RTP packet; receive (320), from the BBIFF device (112), an instruction to forward the RTP packet to a Lawful Interception (LI) Mirror IMS State Function, LMISF, (114) wherein the instruction comprises an associated dedicated bearer identity; and forward (322) the RTP packet to the LMISF (114) with the associated dedicated bearer identity.

10. The network node (400) of claim 9, wherein the IMS traffic comprises signaling packets, and the processing circuitry is further configured to cause the network node(400) to: forward (312) the signaling packets to the LMISF (114).

11. The network node (400) of any one of claims 9 to 10, wherein the IMS traffic received from the BBIFF device (112) comprises a User Equipment, UE, subscriber identity, and wherein the RTP packet that is buffered is associated with the UE subscriber identity, and the RTP packet is forwarded to the LMISF (114) with the UE subscriber identity.

12. The network node (400) of claim 11, wherein the UE subscriber identity is an International Mobile Subscriber Identity, IMSI.

13. The network node (400) of any one of claims 11 to 12, wherein the instruction to forward the RTP packet comprises the UE subscriber identity that identifies the RTP packet.

14. The network node (400) of any one of claims 9 to 13, wherein the DBM HF device (302) is associated with an S8 Home Routing, S8HR, roaming architecture.

15. The network node (400) of any one of claims 9 to 14, wherein the RTP packets are buffered at a temporary UE subscriber identity database (304).

16. The network node (400) of any one of claims 9 to 15, wherein the instruction to forward the RTP packet is concurrent with activation of a dedicated bearer associated with the dedicated bearer identity.

17. A method for buffering Real-time Transport Protocol, RTP, packets performed by a Bearer Binding Intercept and Forward Function, BBIFF, device (112), the method comprising: providing (306), to a Default Bearer Media Handler Function, DBMHF, device (302), Internet Protocol, IP, Multimedia Subsystem, IMS, traffic on a default bearer, wherein the IMS traffic comprises an RTP packet; providing (314) to a Lawful Interception (LI) Mirror IMS State Function, LMISF, (114) a dedicated bearer activation associated with a dedicated bearer; receiving (316), from the LMISF (114), a request to send media on the dedicated bearer; and providing (320), to the DBMHF device, a request to send the RTP packet to the LMISF (114), wherein the request to send the RTP packet comprises a dedicated bearer ID associated with the dedicated bearer.

18. The method of claim 17, wherein the dedicated bearer activation provided to the LMISF (114) comprises a User Equipment, UE, subscriber identity, and the request to send the RTP packet to the LMISF (114) comprises the UE subscriber identity.

19. The method of claim 18, wherein the UE subscriber identity is an International Mobile Subscriber Identity, IMSI.

20. The method of any one of claims 17 to 19, further comprising: providing (318), to the LMISF (114), media associated with the request to send media on the dedicated bearer.

21. The method of claim 20, wherein the providing media is concurrent with providing, to the DBMHF device (302), the request to send the RTP packet to the LMISF (114).

22. A network node (400) that implements a Bearer Binding Intercept and Forward Function, BBIFF, device (112) for buffering Real-time Transport Protocol, RTP, packets, the network node (400) comprising processing circuitry (404) configured to cause the network node (400) to: provide (306), to a Default Bearer Media Handler Function, DBMHF, device (302), Internet Protocol, IP, Multimedia Subsystem, IMS, traffic on a default bearer, wherein the IMS traffic comprises an RTP packet; provide (314) to a Lawful Interception (LI) Mirror IMS State Function, LMISF, (114) a dedicated bearer activation associated with a dedicated bearer; receive (316), from the LMISF (114), a request to send media on the dedicated bearer; and provide (320), to the DBMHF device, a request to send the RTP packet to the LMISF (114), wherein the request to send the RTP packet comprises a dedicated bearer ID associated with the dedicated bearer.

23. The network node (400) of claim 22, wherein the dedicated bearer activation provided to the LMISF (114) comprises a User Equipment, UE, subscriber identity, andthe request to send the RTP packet to the LMISF (114) comprises the UE subscriber identity.

24. The network node (400) of claim 23, wherein the UE subscriber identity is an International Mobile Subscriber Identity, IMSI.

25. The network node (400) of any one of claims 22 to 24, wherein the processing circuitry is further configured to cause the network node (400) to: provide (318), to the LMISF (114), media associated with the request to send media on the dedicated bearer.

26. The network node (400) of claim 25, wherein the providing media is concurrent with providing, to the DBMHF device, the request to send the RTP packet to the LMISF (114).

27. A computer program (410) comprising instructions which, when executed on processing circuitry (404), causes the processing circuitry (404) to carry out the method according to any one of claims 1 to 8 or 17 to 21.

28. A carrier containing the computer program (410) of claim 27, wherein the carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium (406).

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