Methods, systems, and computer readable media for handling internet protocol (ip) multimedia subsystem (ims) registration at proxy call session control function (p-cscf) for roaming users after policy and charging rules function (pcrf) database failure

A system for handling Internet protocol (IP) multimedia subsystem (IMS) registrations at a proxy call session control function (P-CSCF) after a policy and charging rules function (PCRF) database failure, the system comprising:

• a P-CSCF including at least one processor and a memory;
• a user contact registration cache stored in the memory and having entries corresponding to user contacts registered with an IMS network;
• and
• a user contact registration manager stored in the memory and executable by the at least one processor for:
• receiving a session initiation protocol (SIP) REGISTER request message after a PCRF database failure;
• determining that the SIP REGISTER request message is for an existing user;
• and
• in response to determining that the SIP REGISTER request message is for an existing user:
• obtaining a list of user contacts having entries in a registration cache of the P-CSCF corresponding to an address of record in the SIP REGISTER request message;
• testing reachability of the user contacts having user contact entries in the list and determining that at least one of the user contacts is unreachable;
• and
• freeing resources of the P-CSCF for the at least one of the user contacts determined to be unreachable.

A non-transitory computer readable medium having stored thereon executable instructions that when executed by a processor of a computer controls the computer to perform steps comprising:

• receiving, by a proxy call session control function (P-CSCF) and after a policy and charging rules function (PCRF) database failure, a session initiation protocol (SIP) REGISTER request message;
• determining, by the P-CSCF, that the SIP REGISTER request message is for an existing user;
• and
• in response to determining that the SIP REGISTER request message is for an existing user:
• obtaining, by the P-CSCF, a list of user contacts having entries in a registration cache of the P-CSCF corresponding to an address of record in the SIP REGISTER request message;
• testing, by the P-CSCF, reachability of the user contacts in the list and determining that at least one of the user contacts is unreachable;
• and
• freeing, by the P-CSCF, resources of the P-CSCF for the at least one of the user contacts determined to be unreachable.