# US 2021/0345450 A1 · Establishing an ip multimedia subsystem session > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0345450 A1 - Document ID: US20210345450A1 - Status: Published application - Kind: A1 - Application number: 17/374,635 - Filed: 2021-07-13 - Published: 2021-11-04 - Earliest claimed: 2018-04-05 - Assignees: Lenovo (Singapore) Pte. Ltd. - Applicants: Lenovo (Singapore) PTE. LTD. - Inventors: Roozbeh Atarius; Genadi Velev; Dimitrios Karampatsis; Andreas Kunz - Web page: https://patentgrep.com/patent/US20210345450A1 ## CPC - H04L 65/1069: Session establishment or de-establishment - 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 65/1016: IP multimedia subsystem [IMS] - H04L 65/1104: Session initiation protocol [SIP] - H04M 15/66: {Policy and charging system} - H04W 4/08: User group management - H04W 8/08: Mobility data transfer - H04W 28/0236: {radio quality, e.g. interference, losses or delay} - H04W 76/11: Allocation or use of connection identifiers - H04W 36/0011: {for data sessions of end-to-end connection} - H04W 36/144: {over a different radio air interface technology} - 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) - H04M: TELEPHONIC COMMUNICATION (circuits for controlling other apparatus via a telephone cable and not involving telephone switching apparatus G08) ## Abstract Apparatuses, methods, and systems are disclosed for establishing an IP multimedia subsystem session. One method includes receiving, at a first network entity from a user device, a first session initiation protocol message comprising a session description protocol, wherein the first session initiation protocol message is used to establish an internet protocol multimedia subsystem session for an application. The method includes transmitting, from the first network entity to a second network entity, a first message comprising an internet protocol address and an identifier for the application. The method includes receiving, at the first network entity from the second network entity, a status of a radio access technology of the user device, wherein the status of the radio access technology of the user device is received by the second network entity from a third network entity. ## Claims ### Claim 1 A method comprising: receiving, at a first network entity from a user device, a first session initiation protocol message comprising a session description protocol, wherein the first session initiation protocol message is used to establish an internet protocol multimedia subsystem session for an application; transmitting, from the first network entity to a second network entity, a first message comprising an internet protocol address and an identifier for the application; receiving, at the first network entity from the second network entity, a status of a radio access technology of the user device; and transmitting, from the first network entity to the user device, a second session initiation protocol provisional response acknowledgement message based at least party on the status of the radio access technology of the user device, wherein the second session initiation protocol provisional response acknowledgement message confirms the session description protocol or provides a change to the session description protocol. ### Claim 2 (depends on 1) The method of claim 1, wherein the status of the radio access technology of the user device is selected from a group comprising: a loss of the radio access technology; and another radio access technology corresponding to the user device transmitting the first session initiation protocol message. ### Claim 3 (depends on 2) The method of claim 2, wherein, in response to the status of the radio access technology of the user device comprising a loss of the radio access technology, not transmitting the second session initiation protocol provisional response acknowledgement message. ### Claim 4 (depends on 1) The method of claim 1, further comprising anticipating, by the first network entity, a new radio access technology for the user device, wherein the new radio access technology is different from the radio access technology. ### Claim 5 (depends on 4) The method of claim 4, wherein the new radio access technology comprises evolved universal mobile telecommunications system terrestrial radio access technology. ### Claim 6 (depends on 5) The method of claim 5, wherein the radio access technology comprises next generation radio access technology. ### Claim 7 (depends on 1) The method of claim 1, wherein the first network entity comprises a proxy call session control function and an application function. ### Claim 8 (depends on 1) The method of claim 1, wherein the second network entity comprises a policy control function. ### Claim 9 (depends on 1) The method of claim 1, wherein the second network entity transmits a second message to a third network entity, and the second message comprises an update to a protocol data unit session. ### Claim 10 (depends on 9) The method of claim 9, wherein the third network entity comprises a base station. ### Claim 11 (depends on 9) The method of claim 9, wherein the update to the protocol data unit session is related to a policy. ### Claim 12 An apparatus comprising a first network entity, the apparatus comprising: a receiver that receives, at the first network entity from a user device, a first session initiation protocol message comprising a session description protocol, wherein the first session initiation protocol message is used to establish an internet protocol multimedia sub system session for an application; and a transmitter that transmits, from the first network entity to a second network entity, a first message comprising an internet protocol address and an identifier for the application; wherein: the receiver receives, at the first network entity from the second network entity, a status of a radio access technology of the user device; and the transmitter transmits, from the first network entity to the user device, a second session initiation protocol provisional response acknowledgement message based at least party on the status of the radio access technology of the user device, wherein the second session initiation protocol provisional response acknowledgement message confirms the session description protocol or provides a change to the session description protocol. ### Claim 13 (depends on 12) The apparatus of claim 12, further comprising a memory, wherein, in response to the status of the radio access technology indicating a loss of the radio access technology, the memory stores a received session initiation protocol message at the first network entity until the radio access technology is reconnected. ### Claim 14 A method comprising: transmitting, from a user device to a first network entity, a first session initiation protocol message comprising a session description protocol, wherein the first session initiation protocol message is used to establish an internet protocol multimedia subsystem session; and receiving, at the user device from the first network entity, a second session initiation protocol provisional response acknowledgment message based at least partly on a status of a radio access technology of the user device, wherein the first network entity receives the status of the radio access technology of the user device from a second network entity, and the second session initiation protocol provisional message confirms the session description protocol or provides a change to the session description protocol. ### Claim 15 (depends on 14) The method of claim 14, wherein the status of the radio access technology of the user device is selected from a group comprising: a loss of the radio access technology; and another radio access technology corresponding to the user device transmitting the first session initiation protocol message. ### Claim 16 (depends on 15) The method of claim 15, wherein, in response to the status of the radio access technology of the user device comprising a loss of the radio access technology, not receiving the second session initiation protocol provisional response acknowledgement message. ### Claim 17 (depends on 14) The method of claim 14, wherein the first network entity anticipates a new radio access technology for the user device, and the new radio access technology is different from the radio access technology. ### Claim 18 (depends on 17) The method of claim 17, wherein the new radio access technology comprises evolved universal mobile telecommunications system terrestrial radio access technology. ### Claim 19 (depends on 14) The method of claim 14, wherein the second network entity transmits a second message to a third network entity, and the second message comprises an update to a protocol data unit session. ### Claim 20 An apparatus comprising a user device, the apparatus comprising: a transmitter that transmits, from a user device to a first network entity, a first session initiation protocol message comprising a session description protocol, wherein the first session initiation protocol message is used to establish an internet protocol multimedia subsystem session; and a receiver that receives, at the user device from the first network entity, a second session initiation protocol provisional response acknowledgement message based at least partly on a status of a radio access technology of the user device, wherein the first network entity receives the status of the radio access technology of the user device from a second network entity, and the second session initiation protocol provisional response acknowledgement message confirms the session description protocol or provides a change to the session description protocol.