IMS support for non-voice services

1. A processor of a user equipment (UE) configured to perform operations comprising:

determining that a network with which the UE is communicating does not support a voice over packet switch (VoPS) service;

in response to determining the network does not support the VoPS service, determining whether the network supports a first non-voice IP Multimedia Subsystem (IMS) service wherein the first non-voice IMS is an IP Multimedia Subsystem (IMS) Short Messaging Service (SMS);

in response to determining the network does not support the first non-voice IMS service, determining whether the network supports a second non-voice IMS service wherein the second non-voice IMS service is an IMS Rich Communications Service (RCS); and

when the network supports the second non-voice IMS service, initiating an IMS Protocol Data Unit (PDU) session establishment with the network.

2. The processor of claim 1 , wherein the determining whether the network supports the non-voice IMS service is based on a non-voice IMS service information element (IE) received from the network.

3. The processor of claim 2 , wherein the non-voice IMS service IE comprises one of a separate indication for each supported non-voice IMS service or a single indication that the network supports one or more non-voice IMS services.

4. The processor of claim 1 , wherein, when the network does not support the non-voice IMS service, the UE does not initiate an IMS Protocol Data Unit (PDU) session establishment with the network.

5. The processor of claim 1 , wherein the determining whether the network supports the non-voice IMS service is based on information stored in one of a Subscriber Identify Module (SIM) card or an eSIM of the UE.

6. The processor of claim 1 , wherein the determining whether the network supports the non-voice IMS service comprises:

requesting information from an entitlement server deployed on an Internet via a data plane of the network, wherein the information comprises the non-voice IMS services supported by the network.

7. The processor of claim 6 , wherein the operations further comprise:

performing a non-access stratum (NAS) procedure with the network; and

establishing an Internet PDU session with the network.

8. The processor of claim 1 , wherein the determining whether the network supports the non-voice IMS service is based on a previous interaction between the UE and the network.

9. The processor of claim 8 , wherein the previous interaction includes recording an indication of the public land mobile network (PLMN) and tracking area identity (TAI) of the network.

10. The processor of claim 1 , wherein the determining that the network supports the IMS RCS service is based on a non-voice IMS service information element (IE) in a registration accept message.

11. The processor of claim 1 , wherein determining whether the network supports the IMS SMS is based on a first bit of a 1 byte Information Element (IE) and determining whether the network supports the IMS RCS is based on a second bit of the 1 byte IE.

12. A user equipment (UE), comprising:

a transceiver configured to communicate with a network; and

a processor communicatively coupled to the transceiver and configured to perform operations comprising:

determining that the network does not support a voice over packet switch (VoPS) service;

in response to determining the network does not support the VoPS service, determining whether the network supports a first non-voice IP Multimedia Subsystem (IMS) service wherein the first non-voice IMS is an IP Multimedia Subsystem (IMS) Short Messaging Service (SMS);

in response to determining the network does not support the first non-voice IMS service, determining whether the network supports a second non-voice IMS service wherein the second non-voice IMS service is an IMS Rich Communications Service (RCS); and

when the network supports the second non-voice IMS service, initiating an IMS Protocol Data Unit (PDU) session establishment with the network.

13. The UE of claim 12 , wherein the determining whether the network supports the non-voice IMS service is based on a non-voice IMS service information element (IE) received from the network.

14. The UE of claim 12 , wherein the determining whether the network supports the non-voice IMS service is based on information stored in one of a Subscriber Identify Module (SIM) card or an eSIM of the UE.

15. The UE of claim 12 , wherein the determining whether the network supports the non-voice IMS service comprises:

requesting information from an entitlement server deployed on an Internet via a data plane of the network, wherein the information comprises the non-voice IMS services supported by the network.

16. The UE of claim 12 , wherein the determining whether the network supports the non-voice IMS service is based on a previous interaction between the UE and the network.

17. A processor of a user equipment (UE) configured to perform operations comprising:

determining that a network with which the UE is communicating does not support an IP Multimedia Subsystem (IMS) voice over PS (VoPS) service;

initiating an IMS Protocol Data Unit (PDU) session establishment with the network;

receiving an IMS PDU session rejection including a cause code indicating whether the network supports a non-voice IMS service; and

when the cause code indicates the network supports the non-voice IMS service, initiating a second IMS PDU session establishment with the network.

18. The processor of claim 17 , wherein the operations further comprise: when the cause code indicates the network does not support the non-voice IM service, the UE does not initiate a second IMS PDU session establishment with the network.

19. The processor of claim 17 , wherein the non-voice IMS service comprises one of a Short Messaging Service (SMS) over IMS service or a Rich Communications Services (RCS) over IMS service or another service provided via a network slice connected to an IMS Data network name (DNN).

20. The processor of claim 17 , wherein the second IMS PDU session establishment is initiated after a predetermined backoff period from the first IMS PDU session establishment.