Patent ID: 9706019
Date: 2017-07-11
CPC Classifications: H04L

Claim:
1. A method for service processing, comprising: receiving, by a proxy call session control function (P-CSCF), a first session initiation protocol (SIP) INVITE message requesting a service from a user equipment (UE), wherein a registration status of the UE in an IP multimedia subsystem is “registered”; generating, by the P-CSCF, an error response including information for triggering the UE to perform an initial registration when the P-CSCF is unable to contact a first serving call session control function (S-CSCF); sending, by the P-CSCF, the error response to the UE; receiving, by the P-CSCF, from the UE a second SIP INVITE message requesting the same service as the first SIP INVITE message after the UE performed the initial registration; and sending, by the P-CSCF, the second SIP INVITE message to a second S-CSCF.