Patent ID: 8902851

Claim:
A method for supporting the transition of a voice call on a user equipment connected to a packet switched source network to a circuit switch target network, the user equipment using a single radio, comprising the steps of: receiving, from a circuit switch network node, a first invite transition request message at an intermediate server, the first invite transition request message having a single radio voice call continuity request identifier and session description protocol information associated with the connection of the user equipment with the target network, wherein said first invite transition request message is initiated by the circuit switch network node and not at the behest of the user equipment; transmitting the first invite transition request message to an application server, the first invite transition request message having the single radio voice call continuity request identifier, the application server transitioning the support for the user equipment to the circuit switch target network based on the presence of the single radio voice call continuity request identifier; receiving a second invite transition request message at the intermediate server, the second invite transition request message having a single radio voice call continuity request identifier and session description protocol information indicating the use of a circuit switched resource at the target network for a media of the session; and, transmitting the second invite transition request message to the application server, the second invite transition request message having the single radio voice call continuity request identifier such that the application server is capable of correlating the first invite request message with the second invite request message, and the application server releasing resources on the source network after receiving the second invite transition request.