Patent ID: 8289887

Claim:
A late call forwarding method comprising, in an internet protocol multimedia subsystem centralized service (ICS): A1, during a call setting up, an internet protocol multimedia subsystem circuit switch control function (ICCF) receiving a call request from a call session control function (CSCF) serving a called user which registers in a Circuit Switching (CS) domain, the call being referred to as session A; the ICCF acquiring a called user's roaming number and initiating a call, being referred to as session B, to the called user; A2, after receiving a call request of the session B, a visited mobile switch center (VMSC) serving the called user determining that a late call forwarding is needed according to a status of the called user and the called user subscribes a late call forwarding service in the CS domain and the VSMC has calling customized application for mobile network enhanced logic (CAMEL) service data for the called user, then initiating a call to a forwarding target to trigger a calling CAMEL service; and A3: said VMSC exchanging CAMEL messages with said ICCF to inform said ICCF about session associated information and a forwarding reason of the late call forwarding, and when said ICCF determines that the forwarding is needed, said ICCF sending a forwarding indication to the CSCF in response to the session A or not responding to the session A depending on the forwarding reason, and said CSCF forwarding the forwarding indication to a telecom application server (TAS), and the TAS initiating a regular forwarding service according to the received forwarding indication or triggering the call forwarding when receiving no response at an expiration, wherein the VMSC is in the CS domain, and the ICCF, CSCF and TAS are in an internet protocol multimedia subsystem.