Patent ID: 8619547

Claim:
A primary serving call session control function device comprising: a memory to store instructions, and a processor coupled to the memory, wherein the primary serving call session control function device is communicatively coupled to a primary application server, wherein the primary serving call session control function device and the primary application server operate collectively as a primary communication resource available to a communication device communicatively coupled to an internet protocol multimedia subsystem network, and wherein the processor, responsive to executing the instructions, performs operations comprising: receiving a registration request originated by the communication device; obtaining a subscription profile associated with the communication device; transmitting a registration message destined for the primary application server according to the subscription profile; identifying a secondary serving call session control function device communicatively coupled to a secondary application server; and transmitting registration information associated with the communication device to the secondary serving call session control function device, wherein the secondary serving call session control function device and the secondary application server operate collectively as a secondary communication resource available to the communication device to complete a call when a subsequent communication fault causes the primary communication resource to be unavailable, the secondary communication resource being available to the communication device prior to and separate from detection of the communication fault, wherein registration of the communication device with the secondary serving call session control function device is completed prior to detection of the communication fault.