Patent ID: 8059633

Claim:
A method of handling a Session Initiation Protocol (SIP) communication within an IP Multimedia Subsystem, where the communication is subject to a call forwarding operation handled by a SIP Application Server, the method comprising the steps of: receiving a (SIP) message from a first user equipment at a Serving Call/State Control Function serving a second user equipment that is identified by a Request-Universal Resource Identifier (R-URI) of the SIP message; at the Serving Call/State Control Function, adding a URI of the Serving Call/State Control Function to a message route header of the SIP message together with an Original Dialog Identifier, and maintaining at the Serving Call/State Control Function a mapping between the Original Dialog Identifier and said R-URI; forwarding the SIP message to the SIP Application Server; at the SIP Application Server, changing the R-URI of the second user equipment in the SIP message to an R-URI of a third user equipment to which the communication is to be forwarded, adding a forwarding indicator to the SIP message, adding a History Information header to the SIP message including a SIP URI of the second user equipment, and returning the SIP message to the Serving Call/State Control Function; and at the Serving Call/State Control Function, identifying the presence of said forwarding indicator and responsively identifying the R-URI of the second user equipment on the basis of the Original Dialog Identifier contained in the returned SIP message, and processing the SIP message according to an originating procedure using the R-URI of the second user equipment.