Lawful interception for short message service over internet protocol multimedia subsystem network(s)

Abstract

A lawful interception device (22) receives Internet Protocol (IP) Multimedia Subsystem (IMS) messages (18) that are messages of a procedure (13) for transporting a certain Short Message (SM) (14) from an origin device (12-O) to a destination device (12-D) via one or more IMS networks (10O) and that are intercepted as part of a lawful interception service. The IMS messages (18) include at least a submit message (18S) that transports the certain SM (14) from the origin device (12-O) to a Short Message Service (SMS) service center (16), and a deliver message (18D) that transports the certain SM (14) from the SMS service center (16) to the destination device (12-D). The lawful interception device (22) sends intercept-related information (IRI) (26) over a handover interface (28) from the device (24) towards a law enforcement device (24). The IRI (26) comprises information related to interception of the IMS messages (18), including correlation information (30) correlating the IMS messages (18) together as relating to the same SM (14).

Description

[0001] LAWFUL INTERCEPTION FOR SHORT MESSAGE SERVICE OVER INTERNET PROTOCOL MULTIMEDIA SUBSYSTEM NETWORK(S)

[0002] TECHNICAL FIELD

[0003] The present application relates generally to lawful interception, and relates more particularly to lawful interception for Short Message Service (SMS) over Internet Protocol (IP) Multimedia Subsystem (IMS) network(s).

[0004] BACKGROUND

[0005] Lawful Interception (LI) allows law enforcement agencies (LEAs) to obtain data from a communication network pursuant to lawful authority, e.g., a warrant, for the purpose of analysis or evidence. See, e.g., 3rdGeneration Partnership Project (3GPP) Technical Specification (TS) 33.127 v17.1.0 for LI as specified by 3GPP. According to LI, a point of interception (POI) in the communication network intercepts data and transfers the intercepted data to a lawful interception device, e.g., a network mediation device that is the mediator between the communication network and a law enforcement device of an LEA. The intercepted data may include the content of communications and / or intercept-related information (IRI) comprising information associated with communication services involving the LI target. After conditioning the intercepted data for transport, the lawful interception device sends the data over a handover interface to the law enforcement device of an LEA.

[0006] Challenges exist in implementing lawful interception for a Short Message Service (SMS), e.g., as described in 3GPP TS 23.040 v17.2.0. SMS enables messages of limited size to be conveyed to and / or from communication devices, and makes use of a so-called SMS service center (SC) that acts as a store and forward center for Short Messages (SMs). The procedure for SMS to convey a certain SM over one or more Internet Protocol (IP) Multimedia Subsystem (IMS) networks, however, involves multiple IMS messages for that one SM, e.g., including a submit message transporting the SM to the SMS SC and a deliver message transporting the SM from the SMS SC. Since IMS messages are reported to the LEA as standalone events, without any guarantee that the IMS messages are reported in order, the multiplicity of IMS messages related to the same underlying SM jeopardizes and / or complicates LEA processing of intercepted data for discriminating intercepted data based on the SM to which the data relates. If the SM content for each IMS message is reported to the LEA, determining which IMS messages relate to which SMs undesirably requires extensive SM content analysis by the LEA. Worse, if the SM content for each IMS message is not reported to the LEA, it may not even be possible for the LEA to determine which IMS messages relate to which SMs. This proves true especially in complex scenarios where multiple, asynchronous SMs are sent from a machine in rapid sequence, so that the LEA may not even be able to discriminate which IMS messages relate to which SMs using IMS message timestamps.

[0007] SUMMARY

[0008] One object of some embodiments herein is to enable a reduction in the processing complexity, inefficiency, and / or cost imposed on a law enforcement agency as part of lawful interception (LI). Another object of some embodiments herein is to equip law enforcement agencies with additional information that would not otherwise be available in some scenarios where the content of Short Messages is not reported to the law enforcement agencies.

[0009] Some embodiments herein provide a law enforcement agency with correlation information that correlates Internet Protocol (IP) Multimedia Subsystem (IMS) messages as relating to the same Short Message (SM). The correlation information may for example correlate a submit message transporting the SM to the Short Message Service (SMS) service center (SC) and a deliver message transporting the SM from the SMS SC. Providing the law enforcement agency with such correlation information may involve for instance setting a correlation parameter to the same value for each of multiple IMS messages, indicating to the law enforcement agency that those IMS messages are correlated together as relating to the same underlying SM.

[0010] Providing a law enforcement agency with correlation information herein advantageously relieves the law enforcement agency from having to perform extensive SM content analysis to determine which IMS messages relate to which SMs and / or enable such determination even in situations where SM content is not reported to the law enforcement agency. In fact, some embodiments enable this determination even when multiple, asynchronous SMs are sent from a machine in rapid sequence, which would otherwise jeopardize making the determination from message timestamps. Moreover, some embodiments herein reuse existing LI signaling for conveying this correlation information to the law enforcement agency, to reduce the processing complexity, inefficiency, and / or cost imposed on the law enforcement agency for lawful interception.

[0011] More particularly, embodiments herein include a method performed by a lawful interception device for lawful interception. The method comprises receiving Internet Protocol, IP, Multimedia Subsystem, IMS, messages that are messages of a procedure for transporting a certain Short Message, SM, from an origin device to a destination device via one or more IMS networks and that were intercepted as part of a lawful interception service. In some embodiments, the IMS messages include at least a submit message that transports the certain SM from the origin device to a Short Message Service, SMS, service center. In some embodiments, the IMS messages include at least a deliver message that transports the certain SM from the SMS service center to the destination device. The method also comprises sending intercept-related information, IRI, over a handover interface from the lawful interception device towards a law enforcement device. In some embodiments, the IRI comprises information related to interception of the IMS messages, including correlation information that correlates the IMS messages together as relating to the same SM.

[0012] In some embodiments, sending the IRI comprises, for each of the IMS messages, sending message-specific IRI that relates to interception of the IMS message and that includes a correlation parameter as the correlation information. In some embodiments, the correlation parameter is set to the same value in the message-specific IRI for each of the IMS messages, indicating that the IMS messages are correlated together as relating to the same SM.

[0013] In some embodiments, the method also comprises, after receiving the submit message, generating a value of the correlation parameter and setting the correlation parameter in the message-specific IRI for the submit message to the generated value. In some embodiments, the method also comprises, for each of the IMS messages other than the submit messages, including the deliver message, determining that the IMS message also relates to the certain SM and setting the correlation parameter in the message-specific IRI for the IMS message to the same generated value.

[0014] In some embodiments, generating the value of the correlation parameter comprises generating the value as a function of values of IMS message parameters in the submit message. In some embodiments, the IMS message parameters in the submit message whose values are used to generate the value of the correlation parameter include a FROM parameter indicating an origin address or identity of the submit message and a transport protocol destination address parameter indicating a destination address of the SM.

[0015] In some embodiments, determining that the deliver message relates to the certain SM comprises determining that a value of a transport protocol origin address parameter in the deliver message matches the value of the FROM parameter in the submit message. In some embodiments, the transport protocol origin address parameter indicates an origin address of the SM. In some embodiments, determining that the deliver message relates to the certain SM comprises determining that a value of a TO parameter in the deliver message matches the value of the transport protocol destination address parameter in the submit message. In some embodiments, the TO parameter indicates a destination address or identity of the deliver message.

[0016] In some embodiments, the IMS message parameters in the submit message whose values are used to generate the value of the correlation parameter include a user data parameter containing the SM, and determining that the deliver message relates to the certain SM comprises determining that a hash of a value of the user data parameter in the deliver message matches a hash of a value of the user data parameter in the submit message. In some embodiments, the submit message is a Session Initiation Protocol, SIP, message. In some embodiments, the IMS message parameters in the submit message whose values are used to generate the value of the correlation parameter include a Call- 1 D parameter in the submit message indicating an identifier unique to a SIP dialog or registration to which the submit message belongs. In other embodiments, the IMS message parameters in the submit message whose values are used to generate the value of the correlation parameter alternatively or additionally include a correlation number parameter in the submit message indicating a number correlating the submit message and any acknowledgement of the submit message.

[0017] In some embodiments, the IMS messages further include a submit report message sent from the SMS service center to the origin device to confirm the SMS service center received the submit message, and determining that the deliver message relates to the certain SM comprises determining that a value of a service center timestamp parameter in the deliver message matches a value of the service center timestamp parameter in the submit report message. In some embodiments, the value of the service center timestamp parameter indicates a time at which the SMS service center received the submit message. In some embodiments, the IMS messages further include a submit report message sent from the SMS service center to the origin device to confirm the SMS service center received the submit message.

[0018] In some embodiments, the submit message and the submit report message are SIP messages, and determining that the submit report message also relates to the certain SM comprises determining that a value of a In-Reply-To parameter in the submit report message matches a value of a Call-1 D parameter in the submit message. In some embodiments, the IMS messages further include a deliver report message sent from the destination device to the SMS service center to confirm the destination device received the deliver message. In some embodiments, the deliver message and the deliver report message are SIP messages, and determining that the deliver report message also relates to the certain SM comprises determining that a value of an In-Reply-To parameter in the deliver report message matches a value of a Call-1 D parameter in the deliver message.

[0019] In some embodiments, the IRI is sent in Direct Signal Reporting, DSR, messages that each include the correlation parameter, wherein the correlation parameter is a correlations parameter or a calllD.main parameter.

[0020] In some embodiments, the IRI is sent in IRI REPORT messages that each include the correlation parameter. In some embodiments, the correlation parameter is a GPRSCorrelationNumber parameter or a communicationldentityNumber parameter.

[0021] In some embodiments, the IMS messages further include a submit report message sent from the SMS service center to the origin device to positively or negatively acknowledge reception of the submit message by the SMS service center. In other embodiments, the IMS messages further include alternatively or additionally a deliver report message sent from the destination device to the SMS service center to positively or negatively acknowledge reception of the deliver message by the destination device.

[0022] In some embodiments, the submit message is an SMS-SUBMIT message and the deliver message is an SMS-DELIVER message.

[0023] In some embodiments, the lawful interception device implements a lawful interception mediation and delivery function. In some embodiments, the IMS messages are Session Initiation Protocol, SIP, messages.

[0024] Other embodiments herein include a lawful interception device configured for lawful interception. The lawful interception device is configured to receive Internet Protocol, IP, Multimedia Subsystem, IMS, messages that are messages of a procedure for transporting a certain Short Message, SM, from an origin device to a destination device via one or more IMS networks and that were intercepted as part of a lawful interception service. In some embodiments, the IMS messages include at least a submit message that transports the certain SM from the origin device to a Short Message Service, SMS, service center. In some embodiments, the IMS messages include at least a deliver message that transports the certain SM from the SMS service center to the destination device. The lawful interception device is also configured to send intercept-related information, I Rl, over a handover interface from the lawful interception device towards a law enforcement device. In some embodiments, the IRI comprises information related to interception of the IMS messages, including correlation information that correlates the IMS messages together as relating to the same SM.

[0025] In some embodiments, the lawful interception device is configured to perform the steps described above for a lawful interception device.

[0026] In some embodiments, a computer program comprising instructions which, when executed by at least one processor of a law enforcement device, causes the law enforcement device to perform the steps described above for a lawful interception device. In some embodiments, a carrier containing the computer program is one of an electronic signal, optical signal, radio signal, or computer readable storage medium.

[0027] Other embodiments herein include a lawful interception device configured for lawful interception. The lawful interception device comprises communication circuitry and processing circuitry. The processing circuitry is configured to receive Internet Protocol, IP, Multimedia Subsystem, IMS, messages that are messages of a procedure for transporting a certain Short Message, SM, from an origin device to a destination device via one or more IMS networks and that were intercepted as part of a lawful interception service. In some embodiments, the IMS messages include at least a submit message that transports the certain SM from the origin device to a Short Message Service, SMS, service center. In some embodiments, the IMS messages include at least a deliver message that transports the certain SM from the SMS service center to the destination device. The processing circuitry is also configured to send intercept-related information, IRI, over a handover interface from the lawful interception device towards a law enforcement device. In some embodiments, the IRI comprises information related to interception of the IMS messages, including correlation information that correlates the IMS messages together as relating to the same SM.

[0028] In some embodiments, the processing circuitry is configured to perform the steps described above for a lawful interception device. Of course, the present disclosure is not limited to the above features and advantages. Indeed, those skilled in the art will recognize additional features and advantages upon reading the following detailed description, and upon viewing the accompanying drawings.

[0029] BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a block diagram of a lawful interception device configured for lawful interception according to some embodiments.

[0031] Figure 2 is a call flow diagram of an IMS messaging procedure for sending a Short Message from an origin device to a destination device via an SMS SC according to some embodiments.

[0032] Figure 3 is a call flow diagram of an IMS messaging procedure for sending a Short Message from an origin device to a destination device via an SMS SC according to other embodiments.

[0033] Figure 4 is a call flow diagram of an example of a lawful interception device sending IRI that correlates IMS messages relating to the same SM, according to some embodiments.

[0034] Figure 5A is a block diagram of IMS messages that are part of a procedure for sending an SM from an origin device to a destination device via IMS network(s) according to some embodiments.

[0035] Figure 5B is call flow diagram of an example of a lawful interception device sending IRI that correlates IMS messages relating to the same SM, according to some embodiments.

[0036] Figure 5C is a table showing example correlation logic for correlating IMS messages relating to the same SM according to some embodiments.

[0037] Figure 6 is a logic flow diagram of a method performed by a lawful interception device according to some embodiments.

[0038] Figure 7 is a block diagram of a lawful interception device according to some embodiments.

[0039] Figure 8 is a block diagram of an example of a communication system in accordance with some embodiments.

[0040] Figure 9 is a block diagram of a UE according to some embodiments.

[0041] Figure 10 is a block diagram of a network node according to some embodiments.

[0042] Figure 11 is a block diagram of a host which may be an embodiment of the host of Figure 8, in accordance with various aspects described herein.

[0043] Figure 12 is a block diagram of a virtualization environment according to some embodiments.

[0044] DETAILED DESCRIPTION

[0045] Figure 1 shows lawful interception (LI) in a communication system 10 according to some embodiments. As shown, an origin device 12-0 sends a certain Short Message (SM) 14 to a destination device 12-D. The SM 14 is a message of limited size (e.g., 140 bytes) and comprises information conveyed via the Short Message Service (SMS), e.g., as described in 3GPP TS 23.040 v17.2.0. SMS as shown in this regard makes use of a so-called SMS service center (SC) 16 that acts as a store and forward center for the SM 14. The SMS SC 16 in this role receives the SM 14 from the origin device 12-0, stores that SM 14 until the destination device 12-D is available, and then forwards the stored SM 14 to the destination device 12-D when the destination device 12-D is available.

[0046] The SM 14 more particularly is sent from the origin device 12-0 to the destination device 12-D via one or more Internet Protocol (IP) Multimedia Subsystem (IMS) networks 10S. In some embodiments, the origin device 12-0 and / or the destination device 12-D communicate directly with the SMS SC 16 via the IMS network(s) 10S. In other embodiments, though, the origin device 12-0 and / or the destination device 12-D communicate with gateway(s) 15 in the IMS network(s) 10S, with the gateway(s) 15 providing interworking with the SMS SC 16, e.g., via a Mobile Application Part (MAP) protocol or a Diameter protocol.

[0047] The procedure for SMS to convey a certain SM 14 over the IMS network(s) 10S involves multiple IMS messages 18 for that one SM 14. As shown, one or more IMS messages 18 for the SM 14 are communicated between the origin device 12-0 and the SMS SC 16 (or gateway(s) 15), including a so-called submit message 18S that transports the SM 14 from the origin device 12-0 to the SMS SC 16. In addition, one or more IMS messages 18 for the SM 14 are communicated between the SMS SC 16 (or gateway(s) 15) and the destination device 12-D, including a deliver message 18D that transports the SM 14 from the SMS SC 16 to the destination device 12-D. In some embodiments, these IMS messages 18 are Session Initiation Protocol (SIP) messages or other application-layer control messages at a Short Message Transfer Layer (SM-TL) of the SMS protocol stack, e.g., as described in 3GPP TS 23.040 v17.2.0.

[0048] Figure 2 shows one example of a procedure 13 for transporting a certain SM 14 via the IMS network(s) 10S, where that procedure 13 includes multiple IMS messages 18 in general terms. As shown, the procedure 13 includes IMS messages 18-1 , 18-2, 18-3, and 18-4 being communicated between the origin device 12-0 and the SMS SC 16 or gateway(s) 15. And the procedure 13 then also includes IMS messages 18-5, 18-6, 18-7, and 18-8 being communicated between the SMS SC 16 or gateway(s) 15 and the destination device 12-D.

[0049] Figure 3 shows one specific implementation of this procedure 13. In this example, IMS message 18-1 is the submit message 18S for transporting the SM 14 from the origin device 12-0 to the SMS SC 16. IMS message 18-1 may for example encapsulate the SM 14 and / or correspond to the SMS-SUBMIT message described in 3GPP TS 23.040 v17.2.0. IMS message 18-2 is an OK message acknowledging receipt and / or processing of IMS message 18-1 , e.g., in the form of a SIP 200 OK message. IMS message 18-3 is a submit report message positively or negatively acknowledging receipt of the SM 14, e.g., so as to correspond to the SMS-SUBMIT- REPORT message described in 3GPP TS 23.040 v17.2.0. IMS message 18-4 is an OK message acknowledging receipt and / or processing of IMS message 18-3, e.g., in the form of a SIP 200 OK message.

[0050] IMS message 18-5 in Figure 3 is the deliver message 18D for transporting the SM 14 from the SMS SC 16 to the destination device 12-D. IMS message 18-5 may for example encapsulate the SM 14 and / or correspond to the SMS-DELIVER message described in 3GPP TS 23.040 v17.2.0. IMS message 18-6 is an OK message acknowledging receipt and / or processing of IMS message 18-5, e.g., in the form of a SIP 200 OK message. IMS message 18-7 is a deliver report message positively or negatively acknowledging receipt of the SM 14, e.g., so as to correspond to the SMS-DELIVER-REPORT message described in 3GPP TS 23.040 v17.2.0. IMS message 18-8 is an OK message acknowledging receipt and / or processing of IMS message 18-7, e.g., in the form of a SIP 200 OK message.

[0051] Referring back to Figure 1 , no matter the particular types of the IMS messages 18 in the procedure 13, one or more points of interception (POI) 20 in the IMS network(s) 10S intercept the IMS messages 18 as part of a lawful interception service. The POI 20 in turn reports the intercepted IMS messages 18 to a lawful interception (LI) device 22, e.g., in the form of an LI mediation device that implements a LI Mediation and Delivery Function (MDF).

[0052] The lawful interception device 22 is configured to send intercept-related information (I Rl) 26 over a handover interface 28 from the lawful interception device 22 to the law enforcement device 24. The handover interface 28 may for instance be a Handover Interface port 2, e.g., as described in ETSI ES 201 , and / or the IRI 26 may be sent in Direct Signal Reporting (DSR) messages or in IRI REPORT messages. The IRI 26 comprises information related to interception of the IMS messages 18, e.g., information about the destination of the SM 14, information about the origin of the SM 14, the time of the SM 14, etc.

[0053] According to embodiments herein, the IRI 26 notably includes correlation information (info) 30 that correlates the IMS messages 18 together as relating to the same SM 14. With the IMS messages 18 correlated by the correlation information 30 including at least the submit message 18S and the deliver message 18D, for example, the correlation information 30 correlates at least the submit message 18S and the deliver message 18D together as relating to the same SM 14. In some embodiments, the IMS messages 18 correlated by the correlation information 30 also include one or more other IMS messages 18 in the procedure 13 for transporting the SM 14. For example, the IMS messages 18 correlated by the correlation information 30 may also include the submit report message 18-3 sent to the origin device 12-0 to positively or negatively acknowledge reception of the submit message 12S and / or the deliver report message 18-7 sent from the destination device 12-D to positively or negatively acknowledge reception of the deliver message 12D. Alternatively or additionally, the IMS messages 18 correlated by the correlation information 30 may also include one or more OK messages 18-2, 18-4, 18-6, and 18-8 that each acknowledge reception of another message. In fact, in some embodiments, the IMS messages 18 correlated by the correlation information 30 includes each of the IMS messages 18-1 through 18-8 in the procedure 13 shown in Figure 3 for transporting the SM 14 from the origin device 12-0 to the destination device 12-D. In these and other embodiments, then, the correlation information 30 may effectively indicate at least some of the IMS messages 18 that are part of the procedure 13 for transporting the same SM 14.

[0054] Equipped with such correlation information 30, the law enforcement device 24 may process the correlation information 30 in order to determine which IMS messages 18 are correlated together as relating to the same SM 14. From processing the correlation information 30, for example, the law enforcement device 24 may determine that the submit message 18S and the deliver message 18D relate to the same SM 14. The law enforcement device 24 can thereby discriminate between IMS messages 18 on the basis of to which underlying SM each IMS message 18 relates. In some embodiments, once the law enforcement device 24 correlates all the IMS messages 18, the law enforcement device 24 is able to reconstruct the timeline of the SMS 18 exchange between the origin device 12-0 and the destination device 12-D.

[0055] In some embodiments, then, the correlation information 30 reflects the results of analysis by the lawful interception device 22 about which IMS messages 18 relate to which SMs 14, as opposed to simply regurgitating the underlying content of the IMS messages 18 as received by the lawful interception device 22. Providing the law enforcement device 24 with the correlation information 30 therefore advantageously relieves the law enforcement device 24 from having to perform that analysis itself, e.g., by analyzing the content of the SM encapsulated in at least some of the IMS messages 18. Some embodiments accordingly enable a reduction in the processing complexity, inefficiency, and / or cost imposed on a law enforcement agency as part of lawful interception (LI). Moreover, providing the law enforcement device 24 with the correlation information 30 enables the law enforcement device 24 to determine which IMS messages 18 relate to which SMs even in situations where the content of the SMs is not reported to the law enforcement device 24, e.g., because the content is not authorized to be exposed to the law enforcement device 24. Alternatively or additionally, the lawful interception device 22 may be configured to generate the correlation information 30 in a way that even accounts for multiple, asynchronous SMs being sent from a machine in rapid sequence, which would otherwise jeopardize making the determination from message timestamps.

[0056] More particularly, in some embodiments, the correlation information 30 correlates the IMS messages 18 together as relating to the same SM 14, even when the IRI 26 is reported to the law enforcement device 24 on an IMS message by IMS message basis, e.g., even when the IMS messages are effectively reported as standalone events. In one or more such embodiments, for example, the IRI 26 sent to the law enforcement device 24 comprises, for each of the IMS messages 18, message-specific IRI that relates to interception of that IMS message 18. That is, for each IMS message 18 that the lawful interception device 22 receives from the POI 20, the lawful interception device 22 sends message-specific IRI related to interception of that IMS message 18. In this case, the message-specific IRI sent for each of the IMS messages 18 includes correlation information 30 that correlates the IMS message 18 together with zero or more other IMS messages related to the same SM 14. The correlation information 30 included in the message-specific IRI for any given IMS message 18 may for example be set to match the correlation information 30 included in the message-specific IRI for any other IMS message (if any) related to the same SM 14. Correlation information 30 that matches across multiple IMS messages 18 thereby indicates that those multiple IMS messages 18 relate to the same SM 14.

[0057] Figure 4 illustrates one example where the correlation information 30 is realized by a correlation parameter (param) included in each message-specific IRI. As shown in Figure 4, the lawful interception device 22 receives IMS messages 18-1 A through 18-8A that each relate to SM 14A. For those IMS messages 18-1 A - 18-8A, the lawful interception device 22 sends message-specific IRI 26-1 A - 26-8A to the law enforcement device 24. Each message-specific IRI 26-1 A - 26-8A includes a correlation parameter (as correlation information 30) set to the same value (A), indicating that the IMS messages 18-1 A - 18-8A are correlated together as relating to the same SM 14A. In particular, the lawful interception device 22 sends messagespecific IRI 26-1 A that relates to interception of IMS message 18-1 A and that includes the correlation parameter set to the value of A. The lawful interception device 22 also sends message-specific IRI 26-2A that relates to interception of IMS message 18-2A and that also includes the correlation parameter set to the value of A, indicating that the IMS message 18-2A relates to the same SM (SM 14A) as IMS message 18-1 A. The lawful interception device 22 further sends message-specific IRI 26-3A that relates to interception of IMS message 18-3A and that again includes the correlation parameter set to the value of A, indicating that the IMS message 18-3A relates to the same SM (14A) as IMS messages 18-1 A and 18-2A. The lawful interception device 22 continues setting the correlation parameter to the value of A in this same manner, in order to indicate that the IMS messages 18-1 A - 18-8A all relate to the same SM (SM 14A).

[0058] By contrast, the lawful interception device 22 thereafter receives IMS messages 18-1 B through 18-8B that each relate to SM 14B. For those IMS messages 18-1 B - 18-8B, the lawful interception device 22 sends message-specific IRI 26-1 B - 26-8B to the law enforcement device 24. Each message-specific IRI 26-1 B - 26-8B includes a correlation parameter (as correlation information 30) set to the same value (B), indicating that the IMS messages 18-1 B - 18-8B are correlated together as relating to the same SM 14B. Notably, by setting the correlation parameter to a different value (B) than the value to which the correlation parameter was set before, the correlation parameter differentiates the IMS messages 18-1 B - 18-8B as relating to a different SM (14B) than IMS messages 18-1 A - 18-8A. More particularly in this regard, the lawful interception device 22 sends message-specific IRI 26-1 B that relates to interception of IMS message 18-1 B and that includes the correlation parameter set to the value of B. The lawful interception device 22 also sends message-specific IRI 26-2B that relates to interception of IMS message 18-2B and that also includes the correlation parameter set to the value of B, indicating that the IMS message 18-2B relates to the same SM (SM 14B) as IMS message 18-1 B (but a different SM than IMS messages 18-1 A - 18-8A). The lawful interception device 22 further sends message-specific IRI 26-3B that relates to interception of IMS message 18-3B and that again includes the correlation parameter set to the value of B, indicating that the IMS message 18-3B relates to the same SM (14B) as IMS messages 18-1 B and 18-2B (but a different SM than IMS messages 18-1 A - 18-8A). The lawful interception device 22 continues setting the correlation parameter to the value of B in this same manner, in order to indicate that the IMS messages 18-1 B - 18-8B all relate to the same SM (SM 14B) (but a different SM than IMS messages 18-1 A - 18-8A).

[0059] The lawful interception device 22 in the example of Figure 4 sets the correlation parameter to have the same value for any IMS messages that relate to the same SM 14 and to have a different value for any IMS messages that relate to different SMs. The correlation information 30 in these and other embodiments may therefore correlate IMS messages 18 together as relating to the same SM 14 by associating those IMS messages 18 with a common value, e.g., so as to effectively group the IMS messages 18 together. This common value creates commonality between the IMS messages 18 even if the IMS messages 18 are reported to the law enforcement device 24 as standalone events and even if the IMS messages 18 are reported out of order. The common value in some embodiments may effectively represent an identity of a sort of session of IMS messages 18 related to the same SM 14, e.g., in which case the common value may be referred to as an SMS Session ID.

[0060] In some embodiments, the value of the correlation parameter which correlates IMS messages as relating to the same SM 14 is generated by the lawful interception device 22 for the first IMS message that relates to that SM 14. The lawful interception device 22 may for example generate the value as a random or pseudo-random value, e.g., with a high probability of uniqueness across SMs. Or, the lawful interception device 12 may generate the value as a function of values of IMS message parameters in that first IMS message, e.g., so that the value is unique to the first IMS message. Such IMS message parameters may for example include a FROM parameter indicating an origin address or identity of the first IMS message and / or a transport protocol destination address parameter indicating a destination address of the SM 14. The IMS message parameters in some embodiments may also include a timestamp parameter indicating when the first IMS message or the SM 14 was transmitted or received and / or a user data parameter containing the SM 14, e.g., so as to differentiate SMs sent with the same content at different times and / or differentiate SMs sent with different content at the same time. Where the IMS message is a SIP message, the IMS message parameters may alternatively or additionally include a Call- 1 D parameter indicating an identifier unique to a SIP dialog or registration to which the IMS message belongs and / or an Intercept Access Point (IAP) provided correlation number in the IMS message.

[0061] Regardless of how the lawful interception device 22 generates the value of the correlation parameter for the first IMS message, though, the lawful interception device 22 stores the generated value as being associated with that SM 14. Then, when the lawful interception device 22 detects other IMS message(s) as relating to the same SM 14, the lawful interception device 22 sets the correlation parameter in the message-specific I I for the IMS message(s) to that same stored value.

[0062] Figures 5A-5C illustrate an example in which the origin device 12-0 is UE A, the destination device 12-D is UE B, IMS messages 18 are SIP messages at a Short Message Transfer Layer (SM-TL) of the SMS protocol stack as described in 3GPP TS 23.040 v17.2.0, the lawful interception device 22 takes the form of an LI mediation device that implements a LI Mediation and Delivery Function (MDF), and the law enforcement device 24 is generally represented as LEA. In some embodiments, the IMS messages 18 are constructed as otherwise specified by 3GPP TS 24.341 v18.0.0. The SIP messages may for example carry an RP-DATA message as defined in 3GPP TS 24.011 v17.2.0, including SMS headers and SMS user information encoded as otherwise specified in 3GPP TS 23.040 v17.2.0.

[0063] Figure 5A in this regard shows UE A as the origin device 12-0 sends a certain SM 14 to UE B as the destination device 12-D, via the SMS SC 16. In this example, UE A as the origin device 12-0, UE B as the destination device 12-D, and the SMS SC 16 are addressable as:

[0064] Table 1 : Example Addresses

[0065] To realize sending of the SM 14 from UE A to UE B via procedure 13, UE A as the origin device 12-0 sends a first IMS message 18-1 in the form of an SMS-SUMBIT message 18-1 to the SMS SC 16. The SMS-SUBMIT message 18-1 may for example include parameters shown in Table 2:

[0066] Table 2: SMS-SUBMIT Message

[0067] Here, the SMS-SUBMIT message encapsulates the SM 14, with the Text parameter (also referred to as a user data parameter) including the content (i.e., text) of the SM 14. The FROM parameter indicates the an origin address of the SMS-SUBMIT message as being the address of UE A (tel:+155555555) and the TO parameter indicates the destination address of the SMS- SUBMIT message as being the address of the SMS SC 16 (tel:+199999999). The transport protocol (TP) destination address (TP-DA) parameter meanwhile indicates the destination address of the SM 14 as being the address of UE B (123456789).

[0068] With the SMS-SUBMIT message being a SIP message in this example, the SMS- SUBMIT message 18-1 also includes a Call-ID parameter and an Internet Access Provided (IAP) Correlation number parameter. The Call-ID parameter indicates an identifier (abc-123-xyz) unique to the SIP dialog or registration to which the SMS-SUBMIT message 18-1 belongs. The lAP-Correlation number parameter indicates a number (f2bc224521f21a350164d4d50e13a5c8) correlating the SMS-SUBMIT message 18-1 and any 200 OK acknowledgement thereof.

[0069] Figure 5A shows that the SMS SC 16 sends a 200 OK message 18-2 to UE A acknowledging receipt and / or processing of the SMS-SUBMIT message 18-1 .

[0070] The SMS SC 16 also sends an SMS-SUBMIT REPORT message 18-3 to UE A. The SMS-SUBMIT REPORT message 18-3 positively or negatively acknowledges receipt of the SM 14 by the SMS SC 16 (as encapsulated in the SMS-SUBMIT message 18-1 ). The SMS- SUBMIT REPORT message 18-3 may for example include parameters shown in Table 3:

[0071] Table 3: SMS-SUBMIT REPORT Message

[0072] Here, the FROM parameter indicates an origin address of the SMS-SUBMIT REPORT message 18-3 as being the address of the SMS SC 16 (tel:+199999999). And the TO parameter indicates the destination address of the SMS-SUBMIT REPORT message 18-3 as being the address of UE A (tel:+155555555). The TP Service Center Time Stamp (TP-SCTS) parameter indicates a time at which the SMS SC 16 received the SMS-SUBMIT message 18-1 (2022-02-28 14:01 :01 ).

[0073] With the SMS-SUBMIT REPORT message 18-3 being a SIP message in this example, the SMS-SUBMIT REPORT message 18-3 also includes the Call-ID parameter and the Internet Access Provided (IAP) Correlation number parameter. The Call-ID parameter indicates the identifier (abc-456-xyz) unique to the SIP dialog or registration to which the SMS-SUBMIT REPORT message 18-3 belongs, which is shown as different from the SIP dialog or registration to which the SMS-SUBMIT message 18-1 belonged. The In-Reply-To parameter indicates the identifier (abc-123-xyz) of the SIP dialog of the message to which the SMS-SUBMIT REPORT message 18-3 is in reply to; namely, the identifier of the SIP dialog or registration of the SMS- SUBMIT message 18-1 , since the SMS-SUBMIT REPORT is in reply to the SMS-SUBMIT message 18-1. The lAP-Correlation number parameter indicates a number (406ddda9b4a0110d5fb0f1504e2738ad) correlating the SMS-SUBMIT REPORT message 18-3 and any 200 OK acknowledgement thereof.

[0074] Figure 5A further shows that UE A sends a 200 OK message 18-4 to the SMS SC 16 acknowledging receipt and / or processing of the SMS-SUBMIT REPORT message 18-3.

[0075] Next in the procedure 13, the SMS SC 16 at some point forwards the SM 14 to UE B as the destination device 12-D. To do so, the SMS SC 16 sends another IMS message 18-5 in the form of an SMS-DELIVER message 18-5 to UE B. The SMS-DELIVER message 18-5 may for example include parameters shown in Table 4:

[0076] Table 4: SMS-DELIVER Message

[0077] Here, the SMS-DELIVER message encapsulates the SM 14, with the Text parameter (also referred to as a user data parameter) including the content (i.e., text) of the SM 14. The FROM parameter indicates the an origin address of the SMS-DELIVER message as being the address of the SMS SC 16 (tel :+ 123456789). And the TO parameter indicates the destination address of the SMS-DELIVER as being the address of UE B (tel:+199999999). The transport protocol (TP) origin address (TP-OA) parameter meanwhile indicates the origin address of the SM 14 as being the address of UE A (555555555). The TP Service Center Time Stamp (TP-SCTS) parameter indicates a time at which the SMS SC 16 received the corresponding SMS-SUBMIT message 18-1 (2022-02-28 14:01 :01 ).

[0078] With the SMS-DELIVER message 18-5 again being a SIP message in this example, the SMS-DELIVER message 18-5 also includes the Call-ID parameter and the Internet Access Provided (IAP) Correlation number parameter. The Call-ID parameter indicates the identifier (abc-789-xyz) unique to the SIP dialog or registration to which the SMS-DELIVER message 18- 5 belongs, which is shown as different from the SIP dialog or registration to which the SMS- SUBMIT message 18-1 belonged and different from the SIP dialog or registration to which the SMS-SUBMIT REPORT message 18-3 belonged. The lAP-Correlation number parameter indicates a number (72df46e39d4187d198f33ffc1818d29d) correlating the SMS-DELIVER message 18-5 and any 200 OK acknowledgement thereof.

[0079] Figure 5A further shows that UE B sends a 200 OK message 18-6 to the SMS SC 16 acknowledging receipt and / or processing of the SMS-DELIVER message 18-5.

[0080] UE B also sends an SMS-DELIVER REPORT message 18-7 to SMS SC 16. The SMSDELIVER REPORT message 18-7 positively or negatively acknowledges receipt of the SM 14 by UE B (as encapsulated in the SMS-DELIVER message 18-5). The SMS-DELIVER REPORT message 18-7 may for example include parameters shown in Table 5:

[0081] Table 5: SMS-DELIVER REPORT Message

[0082] Here, the FROM parameter indicates an origin address of the SMS-DELIVER REPORT message 18-7 as being the address of UE B (tel :+ 123456789). And the TO parameter indicates the destination address of the SMS-DELIVER REPORT message 18-7 as being the address of the SMS SC 16 (tel:+199999999).

[0083] With the SMS-DELIVER REPORT message 18-7 being a SIP message in this example, the SMS-DELIVER REPORT message 18-7 also includes the Call-ID parameter and the Internet Access Provided (IAP) Correlation number parameter. The Call-ID parameter indicates the identifier (abc-888-xyz) unique to the SIP dialog or registration to which the SMS-DELIVER REPORT message 18-7 belongs, which is shown as different from the SIP dialog or registration to which the SMS-SUBMIT message 18-1 belonged, different from the SIP dialog or registration to which the SMS-SUBMIT REPORT message 18-3 belonged, and different from the SIP dialog or registration to which the SMS-DELIVER message 18-5 belonged. The lAP-Correlation number parameter indicates a number (ac6e847f7775a1 b264baedee56025a9e) correlating the SMS-DELIVER REPORT message 18-7 and any 200 OK acknowledgement thereof.

[0084] Figure 5A further shows that the SMS SC 16 sends a 200 OK message 18-8 to UE B acknowledging receipt and / or processing of the SMS-DELIVER REPORT message 18-7.

[0085] Figure 5B shows that the POI 20 intercepts these IMS messages 18-1 through 18-8 and reports them to the LI-MDF 22 (as the lawful interception device 22) one by one, e.g., as separate lawful interception events. The POI 20 may for example send the IMS messages 18 to the LI-MDF 22 as an X2 IRI.

[0086] After receiving the SMS-SUBMIT message 18-1 , the LI-MDF 22 generates the value of a correlation parameter to include in SMS-SUBMIT intercept-related information (IRI) 26-1 to be sent to the LEA 24 for the SMS-SUBMIT message 18-1. The correlation parameter in this example takes the form of an SMS Session ID. The LI-MDF 22 accordingly generates a new SMS Session ID value to include in the SMS-SUBMIT IRI 26-1 .

[0087] In particular, the LI-MDF 22 retrieves the FROM parameter, the TO parameter, the Call- ID parameter, the TP-DA parameter, the user data parameter containing the text of the SM 14, and the lAP-Correlation number parameter. The LI-MDF 22 generates a new SMS Session ID value from these retrieved parameters. The LI-MDF 22 in some embodiments forms an SMS- Session ID Seed from the concatenation of the retrieved parameters, as shown in Table 6 below, and generates the SMS-Session ID as a function of the SMS-Session ID Seed:

[0088] Table 6: SMS Session ID Generation for SMS-SUBMIT IRI

[0089] The LI-MDF 22 may for example generate the SMS-Session ID as a hash of the SMS-Session ID Seed, so that the SMS-Session ID is unique for the SMS-SUBMIT message 18-1 received. This way, unique SMS Session IDs will be assigned to all IMS messages related to the same SM.

[0090] After generating the SMS-Session ID, the LI-MDF 22 stores the retrieved parameters and / or the generated SMS-Session ID Seed, as well as the SMS-Session ID generated, e.g., in a data structure that associates the SMS-Session ID with the stored parameters and / or SMS- Session ID Seed. The LI-MDF 22 also sets the value of the SMS-Session ID parameter in the SMS-SUBMIT IRI 26-1 to the newly generated SMS-Session ID value, and transmits the SMS- SUBMIT IRI 26-1 to the LEA 24.

[0091] Figure 5C shows the correlation logic that the LI-MDF 22 thereafter uses to correlate the IMS messages 18-1 through 18-8.

[0092] In particular, when the LI-MDF 22 receives the 200 OK message 18-2 as shown in Figure 5B, the LI-MDF 22 determines that the 200 OK message 18-2 relates to the same SM 14 as the SMS-SUBMIT message 18-1. The LI-MDF 22 does so by matching the lAP-Correlation number parameter in the 200 OK message 18-2 with the lAP-Correlation number parameter in the SMS-SUBMIT message 18-1 , as such matching pairs the 200 OK message 18-2 with the SMS-SUBMIT message 18-1 and means that the messages 18-1 , 18-2 relate to the same SM 14. Based on this determination, the LI-MDF 22 sets the value of the SMS-Session ID in the 200 OK IRI 26-2 (to be sent to the LEA 24 for the 200 OK message 18-2) to have the same value as the SMS-Session ID included in the SMS-SUBMIT IRI 26-1 (e82057d724e226304e0cad774d0655b4).

[0093] Later, when the LI-MDF 22 receives the SMS-SUBMIT-REPORT message 18-3, the LI-MDF 22 determines that the SMS-SUBMIT-REPORT message 18-3 relates to the same SM 14 as the SMS-SUBMIT message 18-1. The LI-MDF 22 does so by determining that a value of the In-Reply-To parameter in the SMS-SUBMIT-REPORT message 18-3 matches a value of the Call-ID parameter in the SMS-SUBMIT message 18-1. In some embodiments, the LI-MDF 22 may also determine that a value of the TO parameter in the SMS-SUBMIT-REPORT message 18-3 matches a value of the FROM parameter in the SMS-SUBMIT message 18-1 , and / or that a value of the FROM parameter in the SMS-SUBMIT-REPORT message 18-3 matches a value of the TO parameter in the SMS-SUBMIT message 18-1.

[0094] Based on determining that the SMS-SUBMIT-REPORT message 18-3 relates to the same SM 14 as the SMS-SUBMIT message 18-1 , the LI-MDF 22 sets the value of the SMS- Session ID in the SMS-SUBMIT-REPORT IRI 26-3 (to be sent to the LEA 24 for the SMS- SUBMIT-REPORT message 18-3) to have the same value as the SMS-Session ID included in the SMS-SUBMIT IRI 26-1 related to the SM 14 (e82057d724e226304e0cad774d0655b4), as shown in Table 7:

[0095] SMS SUBMIT REPORT IRI

[0096] Table 7: SMS Session ID Generation for SMS-SUBMIT REPORT IRI

[0097] The LI-MDF 22 also stores the value of the TP-SCTS parameter and the value of the IAP- Correlation number parameter in the SMS-SUBMIT-REPORT message 18-3, for use in matching future IMS messages.

[0098] In this regard, when the LI-MDF 22 receives the 200 OK message 18-4 thereafter, the LI-MDF 22 determines that the 200 OK message 18-4 also relates to the same SM 14 as the SMS-SUBMIT message 18-1 . The LI-MDF 22 does so by matching the lAP-Correlation number parameter in the 200 OK message 18-4 with the lAP-Correlation number parameter stored for the SMS-SUBMIT-REPORT message 18-3, as such matching pairs the 200 OK message 18-4 with the SMS-SUBMIT-REPORT message 18-3 and means that the messages 18-3, 18-4 relate to the same SM 14. Based on this determination, the LI-MDF 22 sets the value of the SMS- Session ID in the 200 OK IRI 26-4 (to be sent to the LEA 24 for the 200 OK message 18-4) to have the same value as the SMS-Session ID included in the SMS-SUBMIT IRI 26-1 (e82057d724e226304e0cad774d0655b4).

[0099] Still later, when the LI-MDF 22 receives the SMS-DELIVER message 18-5, the LI-MDF 22 determines that the SMS-DELIVER message 18-5 also relates to the same SM 14 as the SMS-SUBMIT message 18-1 . In some embodiments, the LI-MDF 22 does so by determining that the value of the TP-OA parameter in the SMS-DELIVER message 18-5 matches the value of the FROM parameter in the SMS-SUBMIT message 18-1 and / or that the value of the TO parameter in the SMS-DELIVER message 18-5 matches the value of the TP-DA parameter in the SMS-SUBMIT message 18-1 . Alternatively or additionally, the LI-MDF 22 may base its determination on the value of the user data or text parameter in the SMS-DELIVER message 18-5 (or a hash thereof) matching the value of the user data or text parameter in the SMS- SUBMIT message 18-1 (or a hash thereof). In yet other embodiments, the LI-MDF 22 may alternatively or additionally base its determination on the value of the TP-SCTS parameter in the SMS-DELIVER message 18-5 matching the value of the TP-SCTS parameter in the SMS- SUBMIT-REPORT message 18-3.

[0100] Regardless, based on determining that the SMS-DELIVER message 18-5 relates to the same SM 14 as the SMS-SUBMIT message 18-1 , the LI-MDF 22 sets the value of the SMS- Session ID in the SMS-DELIVER IRI 26-5 (to be sent to the LEA 24 for the SMS-DELIVER message 18-5) to have the same value as the SMS-Session ID included in the SMS-SUBMIT IRI 26-1 related to the SM 14 (e82057d724e226304e0cad774d0655b4), as shown in Table 7: Table 7: SMS Session ID Generation for SMS-DELIVER IRI

[0101] The LI-MDF 22 also stores the value of the lAP-Correlation number parameter in the SMSDELIVER message 18-5, for use in matching future IMS messages.

[0102] To this point, when the LI-MDF 22 receives the 200 OK message 18-6 thereafter, the LI- MDF 22 determines that the 200 OK message 18-6 also relates to the same SM 14 as the SMS-SUBMIT message 18-1 . The LI-MDF 22 does so by matching the lAP-Correlation number parameter in the 200 OK message 18-6 with the lAP-Correlation number parameter stored for the SMS-DELIVER message 18-5, as such matching pairs the 200 OK message 18-6 with the SMS-DELIVER message 18-5 and means that the messages 18-5, 18-6 relate to the same SM 14. Based on this determination, the LI-MDF 22 sets the value of the SMS-Session ID in the 200 OK IRI 26-6 (to be sent to the LEA 24 for the 200 OK message 18-6) to have the same value as the SMS-Session ID included in the SMS-SUBMIT IRI 26-1 (e82057d724e226304e0cad774d0655b4).

[0103] Finally, when the LI-MDF 22 receives the SMS-DELIVER-REPORT message 18-7, the LI-MDF 22 determines that the SMS-DELIVER-REPORT message 18-7 also relates to the same SM 14 as the SMS-SUBMIT message 18-1 . In some embodiments, the LI-MDF 22 does so by determining that a value of the In-Reply-To parameter in the SMS-DELIVER-REPORT message 18-7 matches a value of the Call-ID parameter in the SMS-DELIVER message 18-5. In some embodiments, the LI-MDF 22 may also determine that a value of the TO parameter in the SMS-DELIVER-REPORT message 18-7 matches a value of the FROM parameter in the SMS-DELIVER message 18-8, and / or that a value of the FROM parameter in the SMSDELIVER-REPORT message 18-7 matches a value of the TO parameter in the SMS-DELIVER message 18-5.

[0104] Regardless, based on determining that the SMS-DELIVER-REPORT message 18-7 relates to the same SM 14 as the SMS-SUBMIT message 18-1 , the LI-MDF 22 sets the value of the SMS-Session ID in the SMS-DELIVER-REPORT IRI 26-7 (to be sent to the LEA 24 for the SMS-DELIVER-REPORT message 18-7) to have the same value as the SMS-Session ID included in the SMS-SUBMIT IRI 26-1 related to the SM 14 (e82057d724e226304e0cad774d0655b4), as shown in Table 8:

[0105] Table 8: SMS Session ID Generation for SMS-DELIVER-REPORT IRI

[0106] The LI-MDF 22 also stores the value of the lAP-Correlation number parameter in the SMSDELIVER-REPORT message 18-7, for use in matching future IMS messages.

[0107] Indeed, when the LI-MDF 22 receives the 200 OK message 18-8 thereafter, the LI-MDF 22 determines that the 200 OK message 18-8 also relates to the same SM 14 as the SMS- SUBMIT message 18-1 . The LI-MDF 22 does so by matching the lAP-Correlation number parameter in the 200 OK message 18-8 with the lAP-Correlation number parameter stored for the SMS-DELIVER-REPORT message 18-7, as such matching pairs the 200 OK message 18-8 with the SMS-DELIVER-REPORT message 18-7 and means that the messages 18-7, 18-8 relate to the same SM 14. Based on this determination, the LI-MDF 22 sets the value of the SMS-Session ID in the 200 OK IRI 26-8 (to be sent to the LEA 24 for the 200 OK message 18- 8) to have the same value as the SMS-Session ID included in the SMS-SUBMIT IRI 26-1 (e82057d724e226304e0cad774d0655b4).

[0108] Although embodiments above have generally described the correlation information 30 as being realized with a correlation parameter, the correlation parameter may be implemented as any parameter(s) in the IRI sent to the law enforcement device 24. The correlation parameter in some embodiments may be implemented as new parameter(s) in the IRI 26. Notably, though, other embodiments herein reuse and / or repurpose existing parameter(s) in the IRI 26 as the correlation parameter described herein, e.g., to correlate IMS messages related to an SM rather than or in addition to correlating messages for a voice call. These other embodiments may for example redefine the meaning of existing parameter(s) in the IRI 26 to convey the correlation information 30, at least under some circumstances, e.g., so as to exploit already available LI standardized mechanisms. That is, some embodiments enable the law enforcement agency to reuse standardized correlation mechanisms available for session-based services to link IMS messages related to the same intercepted SM. By reusing existing LI signaling for conveying this correlation information 30, some embodiments reduce the processing complexity, inefficiency, and / or cost imposed on the law enforcement agency for lawful interception.

[0109] Consider now various example realizations of one or more such embodiments that reuse and / or repurpose existing parameter(s) in the IRI 26 as the correlation parameter described herein.

[0110] In one example realization, the lawful interception device 22 sends the IRI 26 to the law enforcement device 24 in Direct Signal Reporting (DSR) messages that each include the correlation parameter. In this case, the correlation parameter may be implemented using the correlationlD parameter in DSR messages, e.g., according to ATIS 1000678. v2, or using the calllD.main parameter in DSR messages, e.g., according to ATIS-1000678. v3.

[0111] In particular, according to ATIS 1000678. v2, a DSR message is structured as below: DirectSignalReporting ::= SEQUENCE { caseld [0] Caseidentity, iAPSystemld [1] lAPSystemldentity OPTIONAL, timestamp [2] TimeStamp, correlationlD [3] Correlationldentifier, protocolSpecificParameters [4] ProtocolSpecificParameters OPTIONAL, signalingMsg [5] SET OF EncapsulatedSignalingMessage

[0112] } Correlationidentifier ::= OCTET STRING For this version of the ATIS standard, some embodiments herein map the “SMS

[0113] Session ID”, as described above, to the correlationlD parameter of all the DSR messages related to the same SM 14. That is, some embodiments herein reuse the correlationlD parameter to convey the correlation information 30 herein. The LEA is then able to correlate all the IMS messages related to the same intercepted SM using the standard correlationlD parameter. In some embodiments, the correlationlD, also known as Callldentity, in ATIS, uniquely identifies a call, call leg, or session within a system.

[0114] By contrast, according to ATIS-1000678.v3, a DSR message is structured as below:

[0115] DirectSignalReporting SEQUENCE { caseld [0] Caseidentity, lAPSystemld [1] lAPSystemldentityOPTIONAL, timestamp [2] TimeStamp, calllD [3] Callldentity OPTIONAL, direction [4] MessageDirection, location [5] Location OPTIONAL, signalingMsg [6] EncapsulatedSignalingMessage

[0116] Callldentity ::= SEQUENCE { main [0] UTF8String, leg [1] UTF8String OPTIONAL

[0117] } For this version of the ATIS standard, some embodiments herein map the generated “SMS Session ID”, as described above, into the Callldentity. main of all the DSR messages related to the same SM 14. That is, some embodiments herein reuse the Callldentity. main parameter to convey the correlation information 30 herein. And the correlation number received on each IMS message related to the same SM 14 will be mapped into the Call Identity, leg of the DSR messages related to the same SM 14. The LEA will then be able to correlate all the IMS messages related to the same intercepted SM using the Callldentity.main parameter, and use the parameter Callldentity. leg to identify each message of the SMS repertoire.

[0118] In another example realization, the lawful interception device 22 sends the IRI 26 to the law enforcement device 24 in IRI REPORT messages that each include the correlation parameter. In this case, the correlation parameter may be implemented using a GPRSCorrelationNumber parameter or a communicationldentityNumber parameter. That is, some embodiments herein reuse the GPRSCorrelationNumber parameter or the communicationldentityNumber parameter to convey the correlation information 30 herein.

[0119] More particularly, the IRI in some embodiments is sent to the LEA by means of an IRI REPORT message according to 3GGP 3GPP TS 33.108. The structure of the IRI REPORT message in this case is shown below: GPRSCorrelationNumber ::= OCTET STRING (SIZE(8..2O))

[0120] Some embodiments map the “SMS Session ID”, as described above, to the GPRSCorrelationNumber parameter of all the IRI REPORT messages related to the same intercepted SM 14. That is, some embodiments herein reuse the GPRSCorrelationNumber parameter to convey the correlation information 30 herein. The LEA will then be able to correlate all the IMS messages related to the same intercepted SM using the standard the GPRSCorrelationNumber parameter.

[0121] As another example realization, the IRI in some embodiments is sent to the LEA by means of an IRI REPORT message according to ETSI TS 102 232-5 on ETSI TS 102 232-1.

[0122] The IRI REPORT message is transported by means of ETSI 232-1 . Here below it is shown the structure of the PSHeader, which is the part of the IRI-REPORT :

[0123] PSHeader ::= SEQUENCE

[0124] {

[0125] H-psDomainld [0] OBJECT IDENTIFIER, lawfullnterceptionldentifier

[0001] Lawfullnterceptionldentifier, authorizationCountryCode [2] PrintableString (SIZE (2)) OPTIONAL, communicationidentifier [3] Communicationidentifier, sequenceNumber [4] INTEGER (0..4294967295), timeStamp [5] GeneralizedTime OPTIONAL, InterceptionPointlD [6] PrintableString (SIZE (1..8)) OPTIONAL, microSecondTimeStamp [7] MicroSecondTimeStamp OPTIONAL, timeStampQualifier [8] TimeStampQualifier OPTIONAL, extendedlnterceptionPointlD [9] OCTET STRING (SIZE (1 ..65535)) OPTIONAL, networkFunctionldentifier

[0010] OCTET STRING (SIZE (1 ..65535)) OPTIONAL

[0126] Communicationidentifier ::= SEQUENCE

[0127] { networkidentifier [0] Networkidentifier, communicationldentityNumber [1] INTEGER (0..4294967295) OPTIONAL, deliveryCountryCode [2] PrintableString (SIZE (2)) OPTIONAL, cINExtension [3] Correlationvalues OPTIONAL

[0128] }

[0129] For the ETSI standard, some embodiments herein map the “SMS Session ID”, as described above, to the communicationldentityNumber parameter of all the IRI REPORT messages related to the same intercepted SM 14. That is, some embodiments herein reuse the communicationldentityNumber parameter to convey the correlation information 30 herein. The LEAs will then be able to correlate all the IMS messages related to the same intercepted SM using the standard communicationldentityNumber parameter.

[0130] In view of the modifications and variations herein, Figure 6 depicts a method performed by a lawful interception device 22 for lawful interception, in accordance with particular embodiments. The method includes receiving IMS messages 18 that are messages of a procedure 13 for transporting a certain SM 14 from an origin device 12-0 to a destination device 12-D via one or more IMS networks 10S and that were intercepted as part of a lawful interception service (Block 600). In some embodiments, the IMS messages 18 include at least a submit message 18-1 that transports the certain SM 14 from the origin device 12-0 to an SMS SC 16 and a deliver message that transports the certain SM 14 from the SMS service center 16 to the destination device 12-D.

[0131] The method also includes sending intercept-related information, IRI, 26 over a handover interface 28 from the lawful interception device 22 towards a law enforcement device 24 (Block 610). The IRI 26 comprises information related to interception of the IMS messages 18. Notably, the IRI 26 includes correlation information 30 that correlates the IMS messages 18 together as relating to the same SM 14.

[0132] In some embodiments, sending the IRI comprises, for each of the IMS messages, sending message-specific IRI that relates to interception of the IMS message and that includes a correlation parameter as the correlation information. In some embodiments, the correlation parameter is set to the same value in the message-specific IRI for each of the IMS messages, indicating that the IMS messages are correlated together as relating to the same SM.

[0133] In some embodiments, the method also comprises, after receiving the submit message, generating a value of the correlation parameter and setting the correlation parameter in the message-specific IRI for the submit message to the generated value (Block 620). In some embodiments, the method also comprises, for each of the IMS messages other than the submit messages, including the deliver message, determining that the IMS message also relates to the certain SM and setting the correlation parameter in the message-specific IRI for the IMS message to the same generated value (Block 630).

[0134] In some embodiments, generating the value of the correlation parameter comprises generating the value as a function of values of IMS message parameters in the submit message. In some embodiments, the IMS message parameters in the submit message whose values are used to generate the value of the correlation parameter include a FROM parameter indicating an origin address or identity of the submit message and a transport protocol destination address parameter indicating a destination address of the SM.

[0135] In some embodiments, determining that the deliver message relates to the certain SM comprises determining that a value of a transport protocol origin address parameter in the deliver message matches the value of the FROM parameter in the submit message. In some embodiments, the transport protocol origin address parameter indicates an origin address of the SM. In some embodiments, determining that the deliver message relates to the certain SM comprises determining that a value of a TO parameter in the deliver message matches the value of the transport protocol destination address parameter in the submit message. In some embodiments, the TO parameter indicates a destination address or identity of the deliver message.

[0136] In some embodiments, the IMS message parameters in the submit message whose values are used to generate the value of the correlation parameter include a user data parameter containing the SM, and determining that the deliver message relates to the certain SM comprises determining that a hash of a value of the user data parameter in the deliver message matches a hash of a value of the user data parameter in the submit message. In some embodiments, the submit message is a Session Initiation Protocol, SIP, message. In some embodiments, the IMS message parameters in the submit message whose values are used to generate the value of the correlation parameter include a Call- 1 D parameter in the submit message indicating an identifier unique to a SIP dialog or registration to which the submit message belongs. In other embodiments, the IMS message parameters in the submit message whose values are used to generate the value of the correlation parameter alternatively or additionally include a correlation number parameter in the submit message indicating a number correlating the submit message and any acknowledgement of the submit message.

[0137] In some embodiments, the IMS messages further include a submit report message sent from the SMS service center to the origin device to confirm the SMS service center received the submit message, and determining that the deliver message relates to the certain SM comprises determining that a value of a service center timestamp parameter in the deliver message matches a value of the service center timestamp parameter in the submit report message. In some embodiments, the value of the service center timestamp parameter indicates a time at which the SMS service center received the submit message. In some embodiments, the IMS messages further include a submit report message sent from the SMS service center to the origin device to confirm the SMS service center received the submit message.

[0138] In some embodiments, the submit message and the submit report message are SIP messages, and determining that the submit report message also relates to the certain SM comprises determining that a value of a In-Reply-To parameter in the submit report message matches a value of a Call-1 D parameter in the submit message. In some embodiments, the IMS messages further include a deliver report message sent from the destination device to the SMS service center to confirm the destination device received the deliver message. In some embodiments, the deliver message and the deliver report message are SIP messages, and determining that the deliver report message also relates to the certain SM comprises determining that a value of an In-Reply-To parameter in the deliver report message matches a value of a Call-1 D parameter in the deliver message.

[0139] In some embodiments, the IRI is sent in Direct Signal Reporting, DSR, messages that each include the correlation parameter, wherein the correlation parameter is a correlationlD parameter or a calllD.main parameter.

[0140] In some embodiments, the IRI is sent in IRI REPORT messages that each include the correlation parameter. In some embodiments, the correlation parameter is a GPRSCorrelationNumber parameter or a communicationldentityNumber parameter.

[0141] In some embodiments, the IMS messages further include a submit report message sent from the SMS service center to the origin device to positively or negatively acknowledge reception of the submit message by the SMS service center. In other embodiments, the IMS messages further include alternatively or additionally a deliver report message sent from the destination device to the SMS service center to positively or negatively acknowledge reception of the deliver message by the destination device.

[0142] In some embodiments, the submit message is an SMS-SUBMIT message and the deliver message is an SMS-DELIVER message.

[0143] In some embodiments, the lawful interception device implements a lawful interception mediation and delivery function.

[0144] In some embodiments, the IMS messages are Session Initiation Protocol, SIP, messages.

[0145] Embodiments herein also include corresponding apparatuses. Embodiments herein for instance include a lawful interception device 22 configured to perform any of the steps of any of the embodiments described above for the lawful interception device 22.

[0146] Embodiments also include a lawful interception device 22 comprising processing circuitry and power supply circuitry. The processing circuitry is configured to perform any of the steps of any of the embodiments described above for the lawful interception device 22. The power supply circuitry is configured to supply power to the lawful interception device 22.

[0147] Embodiments further include a lawful interception device 22 comprising processing circuitry. The processing circuitry is configured to perform any of the steps of any of the embodiments described above for the lawful interception device 22. In some embodiments, the lawful interception device 22 further comprises communication circuitry.

[0148] Embodiments further include a lawful interception device 22 comprising processing circuitry and memory. The memory contains instructions executable by the processing circuitry whereby the lawful interception device 22 is configured to perform any of the steps of any of the embodiments described above for the lawful interception device 22.

[0149] More particularly, the lawful interception device 22 described above may perform the methods herein and any other processing by implementing any functional means, modules, units, or circuitry. In one embodiment, for example, the lawful interception device 22 comprises respective circuits or circuitry configured to perform the steps shown in Figure 6. The circuits or circuitry in this regard may comprise circuits dedicated to performing certain functional processing and / or one or more microprocessors in conjunction with memory. For instance, the circuitry 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, cache memory, flash memory devices, optical storage devices, etc. Program code stored in memory may include 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 several embodiments. In embodiments that employ memory, the memory stores program code that, when executed by the one or more processors, carries out the techniques described herein.

[0150] Figure 7 for example illustrates a lawful interception device 22 as implemented in accordance with one or more embodiments. As shown, the lawful interception device 22 includes processing circuitry 710 and communication circuitry 720. The communication circuitry 720 is configured to transmit and / or receive information to and / or from one or more other nodes, e.g., via any communication technology. The processing circuitry 710 is configured to perform processing described above, e.g., in Figure 6, such as by executing instructions stored in memory 730. The processing circuitry 710 in this regard may implement certain functional means, units, or modules.

[0151] Those skilled in the art will also appreciate that embodiments herein further include corresponding computer programs.

[0152] A computer program comprises instructions which, when executed on at least one processor of a lawful interception device 22, cause the lawful interception device 22 to carry out any of the respective processing described above. A computer program in this regard may comprise one or more code modules corresponding to the means or units described above.

[0153] Embodiments further include a carrier containing such a computer program. This carrier may comprise one of an electronic signal, optical signal, radio signal, or computer readable storage medium.

[0154] In this regard, embodiments herein also include a computer program product stored on a non-transitory computer readable (storage or recording) medium and comprising instructions that, when executed by a processor of a lawful interception device 22, cause the lawful interception device 22 to perform as described above.

[0155] Embodiments further include a computer program product comprising program code portions for performing the steps of any of the embodiments herein when the computer program product is executed by a lawful interception device 22. This computer program product may be stored on a computer readable recording medium.

[0156] In some embodiments, the origin device 12-0 and / or the destination device 12-D may be configured to access the IMS network(s) 10S via a communication system. Figure 8 shows an example of such a communication system 800 in accordance with some embodiments.

[0157] In the example, the communication system 800 includes a telecommunication network 802 that includes an access network 804, such as a radio access network (RAN), and a core network 806, which includes one or more core network nodes 808. The access network 804 includes one or more access network nodes, such as network nodes 810a and 810b (one or more of which may be generally referred to as network nodes 810), or any other similar 3rdGeneration Partnership Project (3GPP) access nodes or non-3GPP access points. Moreover, as will be appreciated by those of skill in the art, a network node is not necessarily limited to an implementation in which a radio portion and a baseband portion are supplied and integrated by a single vendor. Thus, it will be understood that network nodes include disaggregated implementations or portions thereof. For example, in some embodiments, the telecommunication network 802 includes one or more Open-RAN (ORAN) network nodes. An ORAN network node is a node in the telecommunication network 802 that supports an ORAN specification (e.g., a specification published by the O-RAN Alliance, or any similar organization) and may operate alone or together with other nodes to implement one or more functionalities of any node in the telecommunication network 802, including one or more network nodes 810 and / or core network nodes 808.

[0158] Examples of an ORAN network node include an open radio unit (O-RU), an open distributed unit (O-DU), an open central unit (O-CU), including an O-CU control plane (O-CU- CP) or an O-CU user plane (O-CU-UP), a RAN intelligent controller (near-real time or non-real time) hosting software or software plug-ins, such as a near-real time control application (e.g., xApp) or a non-real time control application (e.g., rApp), or any combination thereof (the adjective “open” designating support of an ORAN specification). The network node may support a specification by, for example, supporting an interface defined by the ORAN specification, such as an A1 , F1 , W1 , E1 , E2, X2, Xn interface, an open fronthaul user plane interface, or an open fronthaul management plane interface. Moreover, an ORAN access node may be a logical node in a physical node. Furthermore, an ORAN network node may be implemented in a virtualization environment (described further below) in which one or more network functions are virtualized. For example, the virtualization environment may include an O-Cloud computing platform orchestrated by a Service Management and Orchestration Framework via an O-2 interface defined by the O-RAN Alliance or comparable technologies. The network nodes 810 facilitate direct or indirect connection of user equipment (UE), such as by connecting UEs 812a, 812b, 812c, and 812d (one or more of which may be generally referred to as UEs 812) to the core network 806 over one or more wireless connections. In the example, the origin device 12-0 and / or the destination device 12-D may be any one of the UE 812a-d.”

[0159] Example wireless communications over a wireless connection include transmitting and / or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and / or other types of signals suitable for conveying information without the use of wires, cables, or other material conductors. Moreover, in different embodiments, the communication system 800 may include any number of wired or wireless networks, network nodes, UEs, and / or any other components or systems that may facilitate or participate in the communication of data and / or signals whether via wired or wireless connections. The communication system 800 may include and / or interface with any type of communication, telecommunication, data, cellular, radio network, and / or other similar type of system. The UEs 812 may be any of a wide variety of communication devices, including wireless devices arranged, configured, and / or operable to communicate wirelessly with the network nodes 810 and other communication devices. Similarly, the network nodes 810 are arranged, capable, configured, and / or operable to communicate directly or indirectly with the UEs 812 and / or with other network nodes or equipment in the telecommunication network 802 to enable and / or provide network access, such as wireless network access, and / or to perform other functions, such as administration in the telecommunication network 802.

[0160] In the depicted example, the core network 806 connects the network nodes 810 to one or more hosts, such as host 816. These connections may be direct or indirect via one or more intermediary networks or devices. In other examples, network nodes may be directly coupled to hosts. The core network 806 includes one more core network nodes (e.g., core network node 808) that are structured with hardware and software components. Features of these components may be substantially similar to those described with respect to the UEs, network nodes, and / or hosts, such that the descriptions thereof are generally applicable to the corresponding components of the core network node 808. Example core network nodes include functions of one or more of a Mobile Switching Center (MSC), Mobility Management Entity (MME), Home Subscriber Server (HSS), Access and Mobility Management Function (AMF), Session Management Function (SMF), Authentication Server Function (AUSF), Subscription Identifier De-concealing function (SIDF), Unified Data Management (UDM), Security Edge Protection Proxy (SEPP), Network Exposure Function (NEF), and / or a User Plane Function (UPF).

[0161] The host 816 may be under the ownership or control of a service provider other than an operator or provider of the access network 804 and / or the telecommunication network 802, and may be operated by the service provider or on behalf of the service provider. The host 816 may host a variety of applications to provide one or more service. Examples of such applications include live and pre-recorded audio / video content, data collection services such as retrieving and compiling data on various ambient conditions detected by a plurality of UEs, analytics functionality, social media, functions for controlling or otherwise interacting with remote devices, functions for an alarm and surveillance center, or any other such function performed by a server.

[0162] As a whole, the communication system 800 of Figure 8 enables connectivity between the UEs, network nodes, and hosts. In that sense, the communication system may be configured to operate according to predefined rules or procedures, such as specific standards that include, but are not limited to: Global System for Mobile Communications (GSM); Universal Mobile Telecommunications System (UMTS); Long Term Evolution (LTE), and / or other suitable 2G, 3G, 4G, 5G standards, or any applicable future generation standard (e.g., 6G); wireless local area network (WLAN) standards, such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards (WiFi); and / or any other appropriate wireless communication standard, such as the Worldwide Interoperability for Microwave Access (WiMax), Bluetooth, Z-Wave, Near Field Communication (NFC) ZigBee, LiFi, and / or any low- power wide-area network (LPWAN) standards such as LoRa and Sigfox.

[0163] In some examples, the telecommunication network 802 is a cellular network that implements 3GPP standardized features. Accordingly, the telecommunications network 802 may support network slicing to provide different logical networks to different devices that are connected to the telecommunication network 802. For example, the telecommunications network 802 may provide Ultra Reliable Low Latency Communication (URLLC) services to some UEs, while providing Enhanced Mobile Broadband (eMBB) services to other UEs, and / or Massive Machine Type Communication (mMTC)ZMassive loT services to yet further UEs.

[0164] In some examples, the UEs 812 are configured to transmit and / or receive information without direct human interaction. For instance, a UE may be designed to transmit information to the access network 804 on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the access network 804. Additionally, a UE may be configured for operating in single- or multi-RAT or multi-standard mode. For example, a UE may operate with any one or combination of Wi-Fi, NR (New Radio) and LTE, i.e. being configured for multi-radio dual connectivity (MR-DC), such as E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network) New Radio - Dual Connectivity (EN-DC).

[0165] In the example, the hub 814 communicates with the access network 804 to facilitate indirect communication between one or more UEs (e.g., UE 812c and / or 812d) and network nodes (e.g., network node 810b). In some examples, the hub 814 may be a controller, router, content source and analytics, or any of the other communication devices described herein regarding UEs. For example, the hub 814 may be a broadband router enabling access to the core network 806 for the UEs. As another example, the hub 814 may be a controller that sends commands or instructions to one or more actuators in the UEs. Commands or instructions may be received from the UEs, network nodes 810, or by executable code, script, process, or other instructions in the hub 814. As another example, the hub 814 may be a data collector that acts as temporary storage for UE data and, in some embodiments, may perform analysis or other processing of the data. As another example, the hub 814 may be a content source. For example, for a UE that is a VR headset, display, loudspeaker or other media delivery device, the hub 814 may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which the hub 814 then provides to the UE either directly, after performing local processing, and / or after adding additional local content. In still another example, the hub 814 acts as a proxy server or orchestrator for the UEs, in particular if one or more of the UEs are low energy loT devices.

[0166] The hub 814 may have a constant / persistent or intermittent connection to the network node 810b. The hub 814 may also allow for a different communication scheme and / or schedule between the hub 814 and UEs (e.g., UE 812c and / or 812d), and between the hub 814 and the core network 806. In other examples, the hub 814 is connected to the core network 806 and / or one or more UEs via a wired connection. Moreover, the hub 814 may be configured to connect to an M2M service provider over the access network 804 and / or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with the network nodes 810 while still connected via the hub 814 via a wired or wireless connection. In some embodiments, the hub 814 may be a dedicated hub - that is, a hub whose primary function is to route communications to / from the UEs from / to the network node 810b. In other embodiments, the hub 814 may be a non-dedicated hub - that is, a device which is capable of operating to route communications between the UEs and network node 810b, but which is additionally capable of operating as a communication start and / or end point for certain data channels.

[0167] Figure 9 shows a UE 900 in accordance with some embodiments. As used herein, a UE refers to a device capable, configured, arranged and / or operable to communicate wirelessly with network nodes and / or other UEs. Examples of a UE include, but are not limited to, a smart phone, mobile phone, cell phone, voice over IP (VoIP) phone, wireless local loop phone, desktop computer, personal digital assistant (PDA), wireless cameras, gaming console or device, music storage device, playback appliance, wearable terminal device, wireless endpoint, mobile station, tablet, laptop, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), smart device, wireless customer-premise equipment (CPE), vehicle, vehicle-mounted or vehicle embedded / integrated wireless device, etc. Other examples include any UE identified by the 3rd Generation Partnership Project (3GPP), including a narrow band internet of things (NB- loT) UE, a machine type communication (MTC) UE, and / or an enhanced MTC (eMTC) UE.

[0168] A UE may support device-to-device (D2D) communication, for example by implementing a 3GPP standard for sidelink communication, Dedicated Short-Range Communication (DSRC), vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), or vehicle-to-everything (V2X). In other examples, a UE may not necessarily have a user in the sense of a human user who owns and / or operates the relevant device. Instead, a UE may represent a device that is intended for sale to, or operation by, a human user but which may not, or which may not initially, be associated with a specific human user (e.g., a smart sprinkler controller). Alternatively, a UE may represent a device that is not intended for sale to, or operation by, an end user but which may be associated with or operated for the benefit of a user (e.g., a smart power meter).

[0169] The UE 900 includes processing circuitry 902 that is operatively coupled via a bus 904 to an input / output interface 906, a power source 908, a memory 910, a communication interface 912, and / or any other component, or any combination thereof. Certain UEs may utilize all or a subset of the components shown in Figure 9. The level of integration between the components may vary from one UE to another UE. Further, certain UEs may contain multiple instances of a component, such as multiple processors, memories, transceivers, transmitters, receivers, etc.

[0170] The processing circuitry 902 is configured to process instructions and data and may be configured to implement any sequential state machine operative to execute instructions stored as machine-readable computer programs in the memory 910. The processing circuitry 902 may be implemented as one or more hardware-implemented state machines (e.g., in discrete logic, field-programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), etc.); programmable logic together with appropriate firmware; one or more stored computer programs, general-purpose processors, such as a microprocessor or digital signal processor (DSP), together with appropriate software; or any combination of the above. For example, the processing circuitry 902 may include multiple central processing units (CPUs).

[0171] In the example, the input / output interface 906 may be configured to provide an interface or interfaces to an input device, output device, or one or more input and / or output devices. Examples of an output device include a speaker, a sound card, a video card, a display, a monitor, a printer, an actuator, an emitter, a smartcard, another output device, or any combination thereof. An input device may allow a user to capture information into the UE 900. Examples of an input device include a touch-sensitive or presence-sensitive display, a camera (e.g., a digital camera, a digital video camera, a web camera, etc.), a microphone, a sensor, a mouse, a trackball, a directional pad, a trackpad, a scroll wheel, a smartcard, and the like. The presence-sensitive display may include a capacitive or resistive touch sensor to sense input from a user. A sensor may be, for instance, an accelerometer, a gyroscope, a tilt sensor, a force sensor, a magnetometer, an optical sensor, a proximity sensor, a biometric sensor, etc., or any combination thereof. An output device may use the same type of interface port as an input device. For example, a Universal Serial Bus (USB) port may be used to provide an input device and an output device.

[0172] In some embodiments, the power source 908 is structured as a battery or battery pack. Other types of power sources, such as an external power source (e.g., an electricity outlet), photovoltaic device, or power cell, may be used. The power source 908 may further include power circuitry for delivering power from the power source 908 itself, and / or an external power source, to the various parts of the UE 900 via input circuitry or an interface such as an electrical power cable. Delivering power may be, for example, for charging of the power source 908. Power circuitry may perform any formatting, converting, or other modification to the power from the power source 908 to make the power suitable for the respective components of the UE 900 to which power is supplied.

[0173] The memory 910 may be or be configured to include memory such as random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), magnetic disks, optical disks, hard disks, removable cartridges, flash drives, and so forth. In one example, the memory 910 includes one or more application programs 914, such as an operating system, web browser application, a widget, gadget engine, or other application, and corresponding data 916. The memory 910 may store, for use by the UE 900, any of a variety of various operating systems or combinations of operating systems. The memory 910 may be configured to include a number of physical drive units, such as redundant array of independent disks (RAID), flash memory, USB flash drive, external hard disk drive, thumb drive, pen drive, key drive, high-density digital versatile disc (HD-DVD) optical disc drive, internal hard disk drive, Blu-Ray optical disc drive, holographic digital data storage (HDDS) optical disc drive, external mini-dual in-line memory module (DIMM), synchronous dynamic random access memory (SDRAM), external micro-DIMM SDRAM, smartcard memory such as tamper resistant module in the form of a universal integrated circuit card (UICC) including one or more subscriber identity modules (SIMs), such as a USIM and / or ISIM, other memory, or any combination thereof. The UICC may for example be an embedded UICC (eUlCC), integrated UICC (iUICC) or a removable UICC commonly known as ‘SIM card.' The memory 910 may allow the UE 900 to access instructions, application programs and the like, stored on transitory or non-transitory memory media, to off-load data, or to upload data. An article of manufacture, such as one utilizing a communication system may be tangibly embodied as or in the memory 910, which may be or comprise a device-readable storage medium.

[0174] The processing circuitry 902 may be configured to communicate with an access network or other network using the communication interface 912. The communication interface 912 may comprise one or more communication subsystems and may include or be communicatively coupled to an antenna 922. The communication interface 912 may include one or more transceivers used to communicate, such as by communicating with one or more remote transceivers of another device capable of wireless communication (e.g., another UE or a network node in an access network). Each transceiver may include a transmitter 918 and / or a receiver 920 appropriate to provide network communications (e.g., optical, electrical, frequency allocations, and so forth). Moreover, the transmitter 918 and receiver 920 may be coupled to one or more antennas (e.g., antenna 922) and may share circuit components, software or firmware, or alternatively be implemented separately.

[0175] In the illustrated embodiment, communication functions of the communication interface 912 may include cellular communication, Wi-Fi communication, LPWAN communication, data communication, voice communication, multimedia communication, short-range communications such as Bluetooth, near-field communication, location-based communication such as the use of the global positioning system (GPS) to determine a location, another like communication function, or any combination thereof. Communications may be implemented in according to one or more communication protocols and / or standards, such as IEEE 802.11 , Code Division Multiplexing Access (CDMA), Wideband Code Division Multiple Access (WCDMA), GSM, LTE, New Radio (NR), UMTS, WiMax, Ethernet, transmission control protocol / internet protocol (TCP / IP), synchronous optical networking (SONET), Asynchronous Transfer Mode (ATM), QUIC, Hypertext Transfer Protocol (HTTP), and so forth.

[0176] Regardless of the type of sensor, a UE may provide an output of data captured by its sensors, through its communication interface 912, via a wireless connection to a network node. Data captured by sensors of a UE can be communicated through a wireless connection to a network node via another UE. The output may be periodic (e.g., once every 15 minutes if it reports the sensed temperature), random (e.g., to even out the load from reporting from several sensors), in response to a triggering event (e.g., when moisture is detected an alert is sent), in response to a request (e.g., a user initiated request), or a continuous stream (e.g., a live video feed of a patient).

[0177] As another example, a UE comprises an actuator, a motor, or a switch, related to a communication interface configured to receive wireless input from a network node via a wireless connection. In response to the received wireless input the states of the actuator, the motor, or the switch may change. For example, the UE may comprise a motor that adjusts the control surfaces or rotors of a drone in flight according to the received input or to a robotic arm performing a medical procedure according to the received input.

[0178] A UE, when in the form of an Internet of Things (loT) device, may be a device for use in one or more application domains, these domains comprising, but not limited to, city wearable technology, extended industrial application and healthcare. Non-limiting examples of such an loT device are a device which is or which is embedded in: a connected refrigerator or freezer, a TV, a connected lighting device, an electricity meter, a robot vacuum cleaner, a voice controlled smart speaker, a home security camera, a motion detector, a thermostat, a smoke detector, a door / window sensor, a flood / moisture sensor, an electrical door lock, a connected doorbell, an air conditioning system like a heat pump, an autonomous vehicle, a surveillance system, a weather monitoring device, a vehicle parking monitoring device, an electric vehicle charging station, a smart watch, a fitness tracker, a head-mounted display for Augmented Reality (AR) or Virtual Reality (VR), a wearable for tactile augmentation or sensory enhancement, a water sprinkler, an animal- or item-tracking device, a sensor for monitoring a plant or animal, an industrial robot, an Unmanned Aerial Vehicle (UAV), and any kind of medical device, like a heart rate monitor or a remote controlled surgical robot. A UE in the form of an loT device comprises circuitry and / or software in dependence of the intended application of the loT device in addition to other components as described in relation to the UE 900 shown in Figure 9.

[0179] As yet another specific example, in an loT scenario, a UE may represent a machine or other device that performs monitoring and / or measurements, and transmits the results of such monitoring and / or measurements to another UE and / or a network node. The UE may in this case be an M2M device, which may in a 3GPP context be referred to as an MTC device. As one particular example, the UE may implement the 3GPP NB-loT standard. In other scenarios, a UE may represent a vehicle, such as a car, a bus, a truck, a ship and an airplane, or other equipment that is capable of monitoring and / or reporting on its operational status or other functions associated with its operation.

[0180] In practice, any number of UEs may be used together with respect to a single use case. For example, a first UE might be or be integrated in a drone and provide the drone’s speed information (obtained through a speed sensor) to a second UE that is a remote controller operating the drone. When the user makes changes from the remote controller, the first UE may adjust the throttle on the drone (e.g. by controlling an actuator) to increase or decrease the drone’s speed. The first and / or the second UE can also include more than one of the functionalities described above. For example, a UE might comprise the sensor and the actuator, and handle communication of data for both the speed sensor and the actuators.

[0181] Figure 10 shows a network node 1000 in accordance with some embodiments. As used herein, network node refers to equipment capable, configured, arranged and / or operable to communicate directly or indirectly with a UE and / or with other network nodes or equipment, in a telecommunication network. Examples of network nodes include, but are not limited to, access points (APs) (e.g., radio access points), base stations (BSs) (e.g., radio base stations, Node Bs, evolved Node Bs (eNBs) and NR NodeBs (gNBs)), O-RAN nodes or components of an O-RAN node (e.g., O-RU, O-DU, O-CU).

[0182] Base stations may be categorized based on the amount of coverage they provide (or, stated differently, their transmit power level) and so, depending on the provided amount of coverage, may be referred to as femto base stations, pico base stations, micro base stations, or macro base stations. A base station may be a relay node or a relay donor node controlling a relay. A network node may also include one or more (or all) parts of a distributed radio base station such as centralized digital units, distributed units (e.g., in an O-RAN access node) and / or remote radio units (RRUs), sometimes referred to as Remote Radio Heads (RRHs). Such remote radio units may or may not be integrated with an antenna as an antenna integrated radio. Parts of a distributed radio base station may also be referred to as nodes in a distributed antenna system (DAS).

[0183] Other examples of network nodes include multiple transmission point (multi-TRP) 5G access nodes, multi-standard radio (MSR) equipment such as MSR BSs, network controllers such as radio network controllers (RNCs) or base station controllers (BSCs), base transceiver stations (BTSs), transmission points, transmission nodes, multi-cell / multicast coordination entities (MCEs), Operation and Maintenance (O&M) nodes, Operations Support System (OSS) nodes, Self-Organizing Network (SON) nodes, positioning nodes (e.g., Evolved Serving Mobile Location Centers (E-SMLCs)), and / or Minimization of Drive Tests (MDTs).

[0184] The network node 1000 includes a processing circuitry 1002, a memory 1004, a communication interface 1006, and a power source 1008. The network node 1000 may be composed of multiple physically separate components (e.g., a NodeB component and a RNC component, or a BTS component and a BSC component, etc.), which may each have their own respective components. In certain scenarios in which the network node 1000 comprises multiple separate components (e.g., BTS and BSC components), one or more of the separate components may be shared among several network nodes. For example, a single RNC may control multiple NodeBs. In such a scenario, each unique NodeB and RNC pair, may in some instances be considered a single separate network node. In some embodiments, the network node 1000 may be configured to support multiple radio access technologies (RATs). In such embodiments, some components may be duplicated (e.g., separate memory 1004 for different RATs) and some components may be reused (e.g., a same antenna 1010 may be shared by different RATs). The network node 1000 may also include multiple sets of the various illustrated components for different wireless technologies integrated into network node 1000, for example GSM, WCDMA, LTE, NR, WiFi, Zigbee, Z-wave, LoRaWAN, Radio Frequency Identification (RFID) or Bluetooth wireless technologies. These wireless technologies may be integrated into the same or different chip or set of chips and other components within network node 1000.

[0185] The processing circuitry 1002 may comprise a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application-specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, software and / or encoded logic operable to provide, either alone or in conjunction with other network node 1000 components, such as the memory 1004, to provide network node 1000 functionality.

[0186] In some embodiments, the processing circuitry 1002 includes a system on a chip (SOC). In some embodiments, the processing circuitry 1002 includes one or more of radio frequency (RF) transceiver circuitry 1012 and baseband processing circuitry 1014. In some embodiments, the radio frequency (RF) transceiver circuitry 1012 and the baseband processing circuitry 1014 may be on separate chips (or sets of chips), boards, or units, such as radio units and digital units. In alternative embodiments, part or all of RF transceiver circuitry 1012 and baseband processing circuitry 1014 may be on the same chip or set of chips, boards, or units.

[0187] The memory 1004 may comprise any form of volatile or non-volatile computer-readable memory including, without limitation, persistent storage, solid-state memory, remotely mounted memory, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), mass storage media (for example, a hard disk), removable storage media (for example, a flash drive, a Compact Disk (CD) or a Digital Video Disk (DVD)), and / or any other volatile or non-volatile, non-transitory device-readable and / or computer-executable memory devices that store information, data, and / or instructions that may be used by the processing circuitry 1002. The memory 1004 may store any suitable instructions, data, or information, including a computer program, software, an application including one or more of logic, rules, code, tables, and / or other instructions capable of being executed by the processing circuitry 1002 and utilized by the network node 1000. The memory 1004 may be used to store any calculations made by the processing circuitry 1002 and / or any data received via the communication interface 1006. In some embodiments, the processing circuitry 1002 and memory 1004 is integrated.

[0188] The communication interface 1006 is used in wired or wireless communication of signaling and / or data between a network node, access network, and / or UE. As illustrated, the communication interface 1006 comprises port(s) / terminal(s) 1016 to send and receive data, for example to and from a network over a wired connection. The communication interface 1006 also includes radio front-end circuitry 1018 that may be coupled to, or in certain embodiments a part of, the antenna 1010. Radio front-end circuitry 1018 comprises filters 1020 and amplifiers 1022. The radio front-end circuitry 1018 may be connected to an antenna 1010 and processing circuitry 1002. The radio front-end circuitry may be configured to condition signals communicated between antenna 1010 and processing circuitry 1002. The radio front-end circuitry 1018 may receive digital data that is to be sent out to other network nodes or UEs via a wireless connection. The radio front-end circuitry 1018 may convert the digital data into a radio signal having the appropriate channel and bandwidth parameters using a combination of filters 1020 and / or amplifiers 1022. The radio signal may then be transmitted via the antenna 1010. Similarly, when receiving data, the antenna 1010 may collect radio signals which are then converted into digital data by the radio front-end circuitry 1018. The digital data may be passed to the processing circuitry 1002. In other embodiments, the communication interface may comprise different components and / or different combinations of components.

[0189] In certain alternative embodiments, the network node 1000 does not include separate radio front-end circuitry 1018, instead, the processing circuitry 1002 includes radio front-end circuitry and is connected to the antenna 1010. Similarly, in some embodiments, all or some of the RF transceiver circuitry 1012 is part of the communication interface 1006. In still other embodiments, the communication interface 1006 includes one or more ports or terminals 1016, the radio front-end circuitry 1018, and the RF transceiver circuitry 1012, as part of a radio unit (not shown), and the communication interface 1006 communicates with the baseband processing circuitry 1014, which is part of a digital unit (not shown).

[0190] The antenna 1010 may include one or more antennas, or antenna arrays, configured to send and / or receive wireless signals. The antenna 1010 may be coupled to the radio front-end circuitry 1018 and may be any type of antenna capable of transmitting and receiving data and / or signals wirelessly. In certain embodiments, the antenna 1010 is separate from the network node 1000 and connectable to the network node 1000 through an interface or port.

[0191] The antenna 1010, communication interface 1006, and / or the processing circuitry 1002 may be configured to perform any receiving operations and / or certain obtaining operations described herein as being performed by the network node. Any information, data and / or signals may be received from a UE, another network node and / or any other network equipment. Similarly, the antenna 1010, the communication interface 1006, and / or the processing circuitry 1002 may be configured to perform any transmitting operations described herein as being performed by the network node. Any information, data and / or signals may be transmitted to a UE, another network node and / or any other network equipment.

[0192] The power source 1008 provides power to the various components of network node 1000 in a form suitable for the respective components (e.g., at a voltage and current level needed for each respective component). The power source 1008 may further comprise, or be coupled to, power management circuitry to supply the components of the network node 1000 with power for performing the functionality described herein. For example, the network node 1000 may be connectable to an external power source (e.g., the power grid, an electricity outlet) via an input circuitry or interface such as an electrical cable, whereby the external power source supplies power to power circuitry of the power source 1008. As a further example, the power source 1008 may comprise a source of power in the form of a battery or battery pack which is connected to, or integrated in, power circuitry. The battery may provide backup power should the external power source fail.

[0193] Embodiments of the network node 1000 may include additional components beyond those shown in Figure 10 for providing certain aspects of the network node’s functionality, including any of the functionality described herein and / or any functionality necessary to support the subject matter described herein. For example, the network node 1000 may include user interface equipment to allow input of information into the network node 1000 and to allow output of information from the network node 1000. This may allow a user to perform diagnostic, maintenance, repair, and other administrative functions for the network node 1000.

[0194] Figure 11 is a block diagram of a host 1100, which may be an embodiment of the host 816 of Figure 8, in accordance with various aspects described herein. As used herein, the host 1100 may be or comprise various combinations hardware and / or software, including a standalone server, a blade server, a cloud-implemented server, a distributed server, a virtual machine, container, or processing resources in a server farm. The host 1100 may provide one or more services to one or more UEs.

[0195] The host 1100 includes processing circuitry 1102 that is operatively coupled via a bus 1104 to an input / output interface 1106, a network interface 1108, a power source 1110, and a memory 1112. Other components may be included in other embodiments. Features of these components may be substantially similar to those described with respect to the devices of previous figures, such as Figures 9 and 10, such that the descriptions thereof are generally applicable to the corresponding components of host 1100.

[0196] The memory 1112 may include one or more computer programs including one or more host application programs 1114 and data 1116, which may include user data, e.g. , data generated by a UE for the host 1100 or data generated by the host 1100 for a UE. Embodiments of the host 1100 may utilize only a subset or all of the components shown. The host application programs 1114 may be implemented in a container-based architecture and may provide support for video codecs (e.g., Versatile Video Coding (VVC), High Efficiency Video Coding (HEVC), Advanced Video Coding (AVC), MPEG, VP9) and audio codecs (e.g., FLAC, Advanced Audio Coding (AAC), MPEG, G.711 ), including transcoding for multiple different classes, types, or implementations of UEs (e.g., handsets, desktop computers, wearable display systems, heads-up display systems). The host application programs 1114 may also provide for user authentication and licensing checks and may periodically report health, routes, and content availability to a central node, such as a device in or on the edge of a core network. Accordingly, the host 1100 may select and / or indicate a different host for over-the-top services for a UE. The host application programs 1114 may support various protocols, such as the HTTP Live Streaming (HLS) protocol, Real-Time Messaging Protocol (RTMP), Real-Time Streaming Protocol (RTSP), Dynamic Adaptive Streaming over HTTP (MPEG-DASH), etc.

[0197] Figure 12 is a block diagram illustrating a virtualization environment 1200 in which functions implemented by some embodiments may be virtualized. In the present context, virtualizing means creating virtual versions of apparatuses or devices which may include virtualizing hardware platforms, storage devices and networking resources. As used herein, virtualization can be applied to any device described herein, or components thereof, and relates to an implementation in which at least a portion of the functionality is implemented as one or more virtual components. Some or all of the functions described herein may be implemented as virtual components executed by one or more virtual machines (VMs) implemented in one or more virtual environments 1200 hosted by one or more of hardware nodes, such as a hardware computing device that operates as a network node, UE, core network node, or host. Further, in embodiments in which the virtual node does not require radio connectivity (e.g., a core network node or host), then the node may be entirely virtualized. In some embodiments, the virtualization environment 1200 includes components defined by the O-RAN Alliance, such as an O-Cloud environment orchestrated by a Service Management and Orchestration Framework via an O-2 interface.

[0198] Applications 1202 (which may alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc.) are run in the virtualization environment Q400 to implement some of the features, functions, and / or benefits of some of the embodiments disclosed herein.

[0199] Hardware 1204 includes processing circuitry, memory that stores software and / or instructions executable by hardware processing circuitry, and / or other hardware devices as described herein, such as a network interface, input / output interface, and so forth. Software may be executed by the processing circuitry to instantiate one or more virtualization layers 1206 (also referred to as hypervisors or virtual machine monitors (VMMs)), provide VMs 1208a and 1208b (one or more of which may be generally referred to as VMs 1208), and / or perform any of the functions, features and / or benefits described in relation with some embodiments described herein. The virtualization layer 1206 may present a virtual operating platform that appears like networking hardware to the VMs 1208.

[0200] The VMs 1208 comprise virtual processing, virtual memory, virtual networking or interface and virtual storage, and may be run by a corresponding virtualization layer 1206. Different embodiments of the instance of a virtual appliance 1202 may be implemented on one or more of VMs 1208, and the implementations may be made in different ways. Virtualization of the hardware is in some contexts referred to as network function virtualization (NFV). NFV may be used to consolidate many network equipment types onto industry standard high volume server hardware, physical switches, and physical storage, which can be located in data centers, and customer premise equipment.

[0201] In the context of NFV, a VM 1208 may be a software implementation of a physical machine that runs programs as if they were executing on a physical, non-virtualized machine. Each of the VMs 1208, and that part of hardware 1204 that executes that VM, be it hardware dedicated to that VM and / or hardware shared by that VM with others of the VMs, forms separate virtual network elements. Still in the context of NFV, a virtual network function is responsible for handling specific network functions that run in one or more VMs 1208 on top of the hardware 1204 and corresponds to the application 1202.

[0202] Hardware 1204 may be implemented in a standalone network node with generic or specific components. Hardware 1204 may implement some functions via virtualization. Alternatively, hardware 1204 may be part of a larger cluster of hardware (e.g. such as in a data center or CPE) where many hardware nodes work together and are managed via management and orchestration 1210, which, among others, oversees lifecycle management of applications 1202. In some embodiments, hardware 1204 is coupled to one or more radio units that each include one or more transmitters and one or more receivers that may be coupled to one or more antennas. Radio units may communicate directly with other hardware nodes via one or more appropriate network interfaces and may be used in combination with the virtual components to provide a virtual node with radio capabilities, such as a radio access node or a base station. In some embodiments, some signaling can be provided with the use of a control system 1212 which may alternatively be used for communication between hardware nodes and radio units.

[0203] Although the computing devices described herein (e.g., UEs, network nodes, hosts) may include the illustrated combination of hardware components, other embodiments may comprise computing devices with different combinations of components. It is to be understood that these computing devices may comprise any suitable combination of hardware and / or software needed to perform the tasks, features, functions and methods disclosed herein. Determining, calculating, obtaining or similar operations described herein may be performed by processing circuitry, which may process information by, for example, converting the obtained information into other information, comparing the obtained information or converted information to information stored in the network node, and / or performing one or more operations based on the obtained information or converted information, and as a result of said processing making a determination. Moreover, while components are depicted as single boxes located within a larger box, or nested within multiple boxes, in practice, computing devices may comprise multiple different physical components that make up a single illustrated component, and functionality may be partitioned between separate components. For example, a communication interface may be configured to include any of the components described herein, and / or the functionality of the components may be partitioned between the processing circuitry and the communication interface. In another example, non-computationally intensive functions of any of such components may be implemented in software or firmware and computationally intensive functions may be implemented in hardware.

[0204] In certain embodiments, some or all of the functionality described herein may be provided by processing circuitry executing instructions stored on in memory, which in certain embodiments may be a computer program product in the form of a non-transitory computer- readable storage medium. In alternative embodiments, some or all of the functionality may be provided by the processing circuitry without executing instructions stored on a separate or discrete device-readable storage medium, such as in a hard-wired manner. In any of those particular embodiments, whether executing instructions stored on a non-transitory computer- readable storage medium or not, the processing circuitry can be configured to perform the described functionality. The benefits provided by such functionality are not limited to the processing circuitry alone or to other components of the computing device, but are enjoyed by the computing device as a whole, and / or by end users and a wireless network generally.

[0205] Notably, modifications and other embodiments of the present disclosure will come to mind to one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the present disclosure is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of this disclosure. Although specific terms may be employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

CLAIMSWhat is claimed is:1 . A method performed by a lawful interception device (22) for lawful interception, the method comprising: receiving (600) Internet Protocol, IP, Multimedia Subsystem, IMS, messages (18) that are messages of a procedure (13) for transporting a certain Short Message, SM, (14) from an origin device (12-0) to a destination device (12-D) via one or more IMS networks (1 OO) and that were intercepted as part of a lawful interception service, wherein the IMS messages (18) include at least: a submit message (18S) that transports the certain SM (14) from the origin device (12-0) to a Short Message Service, SMS, service center (16); and a deliver message (18D) that transports the certain SM (14) from the SMS service center (16) to the destination device (12-D); and sending (610) intercept-related information, IRI, (26) over a handover interface (28) from the lawful interception device (22) towards a law enforcement device (24), wherein the IRI (26) comprises information related to interception of the IMS messages (18), including correlation information (30) that correlates the IMS messages (18) together as relating to the same SM (14).

2. The method of claim 1 , wherein sending the IRI (26) comprises, for each of the IMS messages (18), sending message-specific IRI (26) that relates to interception of the IMS message and that includes a correlation parameter as the correlation information (30), wherein the correlation parameter is set to the same value in the message-specific IRI (26) for each of the IMS messages (18), indicating that the IMS messages (18) are correlated together as relating to the same SM (14).

3. The method of claim 2, further comprising: after receiving the submit message (18S), generating (620) a value of the correlation parameter and setting the correlation parameter in the message-specific IRI (26) for the submit message (18S) to the generated value; and for each of the IMS messages (18) other than the submit messages (18S), including the deliver message (18D), determining (630) that the IMS message also relates to the certain SM (14) and setting the correlation parameter in the message-specific IRI (26) for the IMS message to the same generated value.

4. The method of claim 3, wherein generating the value of the correlation parameter comprises generating the value as a function of values of IMS message parameters in the submit message (18S).

5. The method of claim 4, wherein the IMS message parameters in the submit message (18S) whose values are used to generate the value of the correlation parameter include a FROM parameter indicating an origin address or identity of the submit message (18S) and a transport protocol destination address parameter indicating a destination address of the SM (14), and wherein determining that the deliver message (18D) relates to the certain SM (14) comprises determining that: a value of a transport protocol origin address parameter in the deliver message (18D) matches the value of the FROM parameter in the submit message (18S), wherein the transport protocol origin address parameter indicates an origin address of the SM (14); and a value of a TO parameter in the deliver message (18D) matches the value of the transport protocol destination address parameter in the submit message (18S), wherein the TO parameter indicates a destination address or identity of the deliver message (18D).

6. The method of claim 4-5, wherein the IMS message parameters in the submit message (18S) whose values are used to generate the value of the correlation parameter include a user data parameter containing the SM (14), and wherein determining that the deliver message (18D) relates to the certain SM (14) comprises determining that a hash of a value of the user data parameter in the deliver message (18D) matches a hash of a value of the user data parameter in the submit message (18S).

7. The method of any of claims 4-6, wherein the submit message (18S) is a Session Initiation Protocol, SIP, message, and wherein the IMS message parameters in the submit message (18S) whose values are used to generate the value of the correlation parameter include: a Call-ID parameter in the submit message (18S) indicating an identifier unique to a SIP dialog or registration to which the submit message (18S) belongs; and / or an Internet Access Provider, IAP, provided correlation number parameter in the submit message (18S) indicating a number correlating the submit message (18S) and any acknowledgement of the submit message (18S).

8. The method of any of claims 3-7, wherein the IMS messages (18) further include a submit report message sent from the SMS service center (16) to the origin device (12-0) to confirm the SMS service center (16) received the certain SM (14), and wherein determining that the deliver message (18D) relates to the certain SM (14) comprises determining that a value of a service center timestamp parameter in the deliver message (18D) matches a value of theservice center timestamp parameter in the submit report message, wherein the value of the service center timestamp parameter indicates a time at which the SMS service center (16) received the submit message (18S).

9. The method of any of claims 3-8, wherein the IMS messages (18) further include a submit report message sent from the SMS service center (16) to the origin device (12-0) to confirm the SMS service center (16) received the submit message (18S), wherein the submit message (18S) and the submit report message are SIP messages, and wherein determining that the submit report message also relates to the certain SM (14) comprises determining that a value of a In-Reply-To parameter in the submit report message matches a value of a Call-ID parameter in the submit message (18S).

10. The method of any of claims 3-9, wherein the IMS messages (18) further include a deliver report message sent from the destination device (12-D) to the SMS service center (16) to confirm the destination device (12-D) received the deliver message (18D), wherein the deliver message (18D) and the deliver report message are SIP messages, and wherein determining that the deliver report message also relates to the certain SM (14) comprises determining that a value of a In-Reply-To parameter in the deliver report message matches a value of a Call-ID parameter in the deliver message (18D).11 . The method of any of claims 2-10, wherein the IRI (26) is sent in Direct Signal Reporting, DSR, messages that each include the correlation parameter, wherein the correlation parameter is a correlationlD parameter or a calllD.main parameter.

12. The method of any of claims 2-10, wherein the IRI (26) is sent in IRI REPORT messages that each include the correlation parameter, wherein the correlation parameter is a GPRSCorrelationNumber parameter or a communicationldentityNumber parameter.

13. The method of any of claims 1 -12, wherein the IMS messages (18) further include: a submit report message sent from the SMS service center (16) to the origin device (12- O) to positively or negatively acknowledge reception of the submit message (18S) by the SMS service center (16); and / or a deliver report message sent from the destination device (12-D) to the SMS service center (16) to positively or negatively acknowledge reception of the deliver message (18D) by the destination device (12-D).

14. The method of any of claims 1 -13, wherein the submit message (18S) is an SMS- SUBMIT message and the deliver message (18D) is an SMS-DELIVER message.

15. The method of any of claims 1 -14, wherein the lawful interception device (22) implements a lawful interception mediation and delivery function.

16. The method of any of claims 1 -15, wherein the IMS messages (18) are Session Initiation Protocol, SIP, messages.

17. A lawful interception device (22) configured for lawful interception, the lawful interception device (22) configured to: receive Internet Protocol, IP, Multimedia Subsystem, IMS, messages (18) that are messages of a procedure (13) for transporting a certain Short Message, SM, (14) from an origin device (12-0) to a destination device (12-D) via one or more IMS networks (100) and that were intercepted as part of a lawful interception service, wherein the IMS messages (18) include at least: a submit message (18S) that transports the certain SM (14) from the origin device (12-0) to a Short Message Service, SMS, service center (16); and a deliver message (18D) that transports the certain SM (14) from the SMS service center (16) to the destination device (12-D); and send intercept-related information, IRI, (26) over a handover interface (28) from the lawful interception device (22) towards a law enforcement device (24), wherein the IRI (26) comprises information related to interception of the IMS messages (18), including correlation information (30) that correlates the IMS messages (18) together as relating to the same SM (14).

18. The lawful interception device (22) of claim 17, configured to perform the method of any of claims 2-16.

19. A computer program comprising instructions which, when executed by at least one processor of a law enforcement device (24), causes the law enforcement device (24) to perform the method of any of claims 1 -16.

20. A carrier containing the computer program of claim 19, wherein the carrier is one of an electronic signal, optical signal, radio signal, or computer readable storage medium.21 . A lawful interception device (22) configured for lawful interception, the lawful interception device (22) comprising: communication circuitry (720); and processing circuitry (710) configured to:receive Internet Protocol, IP, Multimedia Subsystem, IMS, messages (18) that are messages of a procedure (13) for transporting a certain Short Message, SM, (14) from an origin device (12-0) to a destination device (12-D) via one or more IMS networks (100) and that were intercepted as part of a lawful interception service, wherein the IMS messages (18) include at least: a submit message (18S) that transports the certain SM (14) from the origin device (12-0) to a Short Message Service, SMS, service center (16); and a deliver message (18D) that transports the certain SM (14) from the SMS service center (16) to the destination device (12-D); and send intercept-related information, IRI, (26) over a handover interface (28) from the lawful interception device (22) towards a law enforcement device (24), wherein the IRI (26) comprises information related to interception of the IMS messages (18), including correlation information (30) that correlates the IMS messages (18) together as relating to the same SM (14).

22. The lawful interception device (22) of claim 21 , wherein the processing circuitry (710) is configured to perform the method of any of claims 2-16.

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