Patent ID: 11910474
Assignee: T-MOBILE USA, INC.
Field: Digital communication (Electrical engineering)
Classification: CPC H | IPC H

Claim 9:
10. 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.