IM-SSF IP Multimedia - Service Switching Function
The IM Basic Call State Models are used to define the call processing architecture within the IMS that is recognizable to the CSE and are identical to those defined for call control in traditional network functions such as the MSC (Mobile Switching Centre). The Basic Call State Models are logically located within the IM-SSF which performs the mapping process between SIP methods passed across the ISC and Detection Points that will be used to initiate dialogue with the CSE.
