IMS selection for multi-HSS route advance

A computing system comprising:

• one or more processors;
• and
• one or more non-transitory computer-readable media storing computer-executable instructions that, when executed by the one or more processors, cause the one or more processors to perform actions comprising:
• receiving, by a proxy call session control function (P-CSCF), a request for service from a user equipment (UE) associated with a home subscriber server (HSS) of a plurality of HSSs;
• sending, by the P-CSCF, the request to an assigned serving CSCF (S-CSCF1) associated with the UE;
• upon failing to receive, by the P-CSCF, a response from the S-CSCF1 within a preset time period, sending the request to an interrogating CSCF (I-CSCF);
• and
• based on information included in the request, performing, by the I-CSCF, one of:
• discovering an address of a second S-CSCF (S-CSCF2) from the associated HSS and sending the request to the S-CSCF2 based on the discovered address of the S-CSCF2, or
• sending, to the P-CSCF, a message indicative of the requested service being unavailable,
• wherein the information indicates whether the HSS associated with the UE supports custom route advance (RA) logic, and the I-CSCF performs the discovering when the HSS supports the custom RA logic and performs the sending when the HSS does not support the custom RA logic.

One or more non-transitory computer-readable media storing computer-executable instructions that, when executed by one or more processors, cause the one or more processors to perform actions comprising:

• receiving, by a proxy call session control function (P-CSCF), a request for service from a user equipment (UE) associated with a home subscriber server (HSS) of a plurality of HSSs;
• sending, by the P-CSCF, the request to a first serving CSCF (S-CSCF1) associated with the UE;
• upon failing to receive, by the P-CSCF, a response from the S-CSCF1 within a preset time period, sending the request to an interrogating CSCF (I-CSCF);
• and
• based on information included in the request, performing, by the I-CSCF, one of:
• discovering an address of a second S-CSCF (S-CSCF2) from the associated HSS and sending the request to the S-CSCF2 based on the discovered address of the S-CSCF2, or
• sending, to the P-CSCF, a message indicative of the requested service being unavailable,
• wherein the information indicates whether the HSS associated with the UE supports custom route advance (RA) logic, and the I-CSCF performs the discovering when the HSS supports the custom RA logic and performs the sending when the HSS does not support the custom RA logic.