Methods for routing of calls in internet protocol multimedia subsystem centralized services networks and related gateway mobile switching centres (GMSC) and home location registers (HLR)

摘要

Methods for routing a call involving an Internet Protocol (IP) Multimedia Subsystem Centralized Services (ICS) subscriber accessing an IP Multimedia Subsystem (IMS) network using a circuit switched (CS) access network are provided. The method includes receiving an incoming call request for a user at a gateway Mobile Switching Centre (GMSC); accessing a Location Register storing information relating to the user to determine if the user is an ICS subscriber; and generating and forwarding a SIP INVITE message to the IMS to establish the call if it is determined that the user is an ICS subscriber. Related Gateway Mobile Switching Centres (GMSCs) and Home Location Registers (HLR) are also provided herein.