Patent ID: 9083714
Filing Date: 2015-07-14
Classification: H04L

Abstract:
1. A method for restoration of an IP Multimedia Subsystem (IMS) network upon unavailability of a Proxy Call Session Control Function (P-CSCF) server, wherein one or more user equipment (UE) accesses the IMS network through the P-CSCF server, the method comprising: establishing, by a Policing and Charging Enforcement Function (PCEF) server, an IP Connectivity Access Network (IP-CAN) session with a UE; submitting, from the PCEF server to the UE, a first list of available P-CSCF servers; capturing, by the PCEF server, a first registration message submitted from the UE towards a first P-CSCF server selected from the first list of available P-CSCF servers, extracting from the first registration message an identifier of the first P-CSCF server, and storing the identifier of the first P-CSCF server; upon successful registration of the UE through the first P-CSCF server, capturing, by the PCEF server, a successful registration response message submitted from the first P-CSCF server towards the UE, and associating the identifier of the first P-CSCF server with the UE; monitoring, by the PCEF server, the availability of the first P-CSCF server; and upon detecting unavailability of the first P-CSCF server by the PCEF, submitting from the PCEF server a second list of available P-CSCF servers, which excludes the unavailable first P-CSCF server, towards every UE associated with the identifier of the first P-CSCF server.