Patent ID: 8923247
Filing Date: 2014-12-30
Classification: H04W

Abstract:
1. A method for handing over a call of a mobile entity that is circuit switched attached via a mobile switching center located in a visited network to an IP multimedia subsystem, wherein the mobile entity is registered at the IP multimedia subsystem, the method comprising: receiving, by the mobile switching center, a hand over request message from a radio access for handing over the call from the circuit switched attachment to the IP multimedia subsystem to a packet switched attachment to the IP multimedia subsystem, wherein the hand over request message includes an information that the hand over is a single radio voice call continuity hand over, the mobile switching center comprising a visited session transfer function that controls the hand over from circuit switched to packet switched, transmitting, by the mobile switching center, to a source servicing GPRS support node in a visited network to which said mobile entity is currently connected to, a first hand over command to switch from the circuit switched to the packet switched attachment to the IP multimedia subsystem, in response to said hand over request message, transmitting, by the mobile switching center, a second hand over command to the mobile entity instructing a hand over from the circuit switched to the packet switched attachment, and instructing, by the mobile switching center, a media gateway to transmit media data on a bearer provided for said packet switched attachment, wherein the call is anchored in a visited session transfer function provided in the mobile switching center during the circuit switched and the packet switched attachment to the IP multimedia subsystem without routing signalling messages to the home network of the mobile entity.