# US 11,310,287 B2 · Methods and nodes in a lawful interception system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,310,287 B2 - Document ID: US11310287B2 - Status: Granted - Kind: B2 - Application number: 16/498,077 - Filed: 2017-04-26 - Published: 2020-01-23 - Granted: 2022-04-19 - Earliest claimed: 2017-04-26 - Assignees: Telefonaktiebolaget LM Ericsson (publ) - Applicants: Telefonaktiebolaget LM Ericsson (publ) - Inventors: Luciano Orabona; Pompeo Santoro; Andrea Senatore; Elvira Villani - Web page: https://patentgrep.com/patent/US11310287B2 ## CPC - H04L 65/1083: In-session procedures - H04L 63/306: {intercepting packet switched data communications, e.g. Web, Internet or IMS communications} - H04L 65/1016: IP multimedia subsystem [IMS] - H04L 65/103: {in the network} - H04L 65/1104: Session initiation protocol [SIP] - H04W 80/10: adapted for {application} session management, e.g. SIP [Session Initiation Protocol] {(connection management H04W76/00; arrangements for session management H04L67/14)} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract The present disclosure relates to the problem to deliver correlation information, CN, in case of CC delivery in TDM format to a Monitoring Centers, MC in a circuit switched network and achieving a minimal impact to MCs and/or no impact on the operator network at all. Said problem is solved by using the extension field of calling or called party number for providing the correlation number to a MC from a Mediation Function entity. ## Claims ### Claim 1 A method of operating a Mediation Function (MF) node of a Lawful Intercept (LI) system, the MF being configured to deliver received Content of Communication (CC) and Intercept Related Information (IRI) to a Monitoring Center (MC) monitoring a target's sessions, the MC being situated in and supported by a circuit switched (CS) communications system; the method comprising: receiving IRI and CC of a target's session intercepted during a VoIP session; generating a correlation number (CN) for the IRI and CC of the intercepted session; retrieving, if MC is in a CS system, the calling party number of the MF and/or the called party number of the MC; inserting the CN in an extension field of the calling or called party number; initiating, after receiving the CC, a CC transmission session via a Session Initiating Protocol (SIP) call to the MC by sending a SIP invitation comprising CN in the extension field of the called party number or of the calling party number towards a Border Gateway Control Function (BGCF) node for selecting a Media Gateway; and sending, to the MC: CC packets over Handover Interface HI3 via the selected Media Gateway for the Media Gateway to convert the CC packet format into Time-Division Multiplexing (TDM) format; and IRI over Handover Interface HI2 using the same CN. ### Claim 2 (depends on 1) The method of claim 1, wherein the CN is a Communication-Identity-Number according to LI standards. ### Claim 3 (depends on 1) The method of claim 1, wherein the CN is a real Correlation Number according to LI standards. ### Claim 4 (depends on 1) The method of claim 1, wherein the calling party number of the MF or the called party number of the MC is predefined as a Private Automatic Branch eXchange (PABX) number. ### Claim 5 A method of operating a Monitoring Center (MC) of a Lawful Intercept (LI) system, wherein the MC is situated in and supported by a circuit switched (CS) communications system; the method comprising: receiving Content of Communication (CC) and Intercept Related Information (IRI) from a Mediation Function (MF) node; receiving a correlation number (CN) of a target's session in an extension field of a called party number or of a calling party number in an initiate address message, wherein the CN is associated with the IRI and the CC; searching for the CN in the extension field in the calling party number or in the called party number; accepting a transmission session with the MF if the CN is identified in an extension field; and receiving, from the target's session: converted Time Domain Multiplexing (TDM) traffic from the MF over Handover Interface HI3 via a Media Gateway node; and IRI over Handover Interface HI2 from the MF using the same CN. ### Claim 6 (depends on 5) The method of claim 5, wherein the CN is a Communication-Identity-Number according to LI standards. ### Claim 7 (depends on 5) The method of claim 5, wherein the CN is a real Correlation Number according to LI standards. ### Claim 8 (depends on 5) The method of claim 5, wherein the calling party number or the called party number is predefined as a Private Automatic Branch eXchange (PABX) number. ### Claim 9 A Mediation Function (MF) node of a Lawful Intercept (LI) system; the MF being configured to deliver received Content of Communication (CC) and Intercept Related Information (IRI) to a Monitoring Center (MC) monitoring a target's sessions; the MC being situated in and supported by a circuit switched (CS) communications system; the MF node comprising: a communication interface configured to receive IRI and CC of a target's session intercepted during a VoIP session; processing circuitry operatively connected to the communication interface and configured to: generate a correlation number (CN) for the IRI and CC of the intercepted session; retrieve, if MC is in a CS system, the calling party number or the called party number; inserting the CN in an extension field of the calling or called party number; and initiate, after receiving the CC, a CC transmission session via a Session Initiating Protocol (SIP) call to the MC by sending a SIP invitation comprising CN in the extension field of the called party number or of the calling party number towards a Border Gateway Control Function (BGCF) node for selecting a Media Gateway (MGW); wherein the communication interface is further configured to send to the MC: CC packets over Handover Interface HI3 via the selected Media Gateway for the Media Gateway to convert the CC packet format into Time-Division Multiplexing (TDM) format; and IRI over Handover Interface HI2 using the same CN. ### Claim 10 (depends on 9) The MF node of claim 9, wherein the CN is a Communication-Identity-Number according to LI standards. ### Claim 11 (depends on 9) The MF node of claim 9, wherein the CN is a real Correlation Number according to LI standards. ### Claim 12 (depends on 9) The MF node of claim 9, wherein the calling party number or the called party number is predefined as a Private Automatic Branch eXchange (PABX) number. ### Claim 13 A Monitoring Center (MC) node of a Lawful Intercept (LI) system; wherein the MC is situated in and supported by a circuit switched (CS) communications system; the MC node comprising: a communication interface configured to: receive Content of Communication (CC) and Intercept Related Information (IRI) from an Mediation Function (MF) node; and receive a correlation number (CN) of a target's session in an extension field of a called party number or of a calling party number in an initiate address message, wherein the CN is associated with the IRI and the CC; and processing circuitry operatively connected to the communication interface and configured to: search for the CN in the extension field in the calling party number or called party number; and accept, if the CN is identified in an extension field, a transmission session with the MF; wherein the communication interface is further configured to receive from the MF: Time-Division Multiplex (TDM) traffic over Handover Interface HI3 via a Media Gateway; and IRI over Handover Interface HI2 using the same CN. ### Claim 14 (depends on 13) The MC node of claim 13, wherein the CN is a Communication-Identity-Number according to LI standards. ### Claim 15 (depends on 13) The MC node of claim 13, wherein the CN is a real Correlation Number according to LI standards. ### Claim 16 (depends on 13) The MC node of claim 13, wherein the calling party number or the called party number is predefined as a Private Automatic Branch eXchange (PABX) number.