Method and appliance to assign application servers in an ims.

A method for assigning an Application Server with Session Initiation Protocol to a subscriber within an IP Multimedia Subsystem, the method comprising: identifying in a Local Subscriber Server a set of initial filtering criteria provisioned for said subscriber, containing the cited set of initial filtering criteria at least one Application Server identity with Session Initiation Protocol; send the aforementioned set of initial filtering criteria of the Local Subscriber Server to a Call Control / Service Session Function; receiving the aforementioned set of initial filtering criteria in said Call Control / Service Session Function and resolving said Application Server identity with Session Initiation Protocol in a plurality of Application Server addresses; assign one of said addresses to said subscriber for use in providing a service to said subscriber; temporarily store the address assigned in the Call Control / Service Session Function for said subscriber for subsequent use; and sending a SIP message from the Call Control / Service Session Function to the application server and said assigned address, characterized in that When the said SIP message is received on the application server, the address of the application server is stored as non-transparent data on the Local Subscriber Server, over the Sh interface.