Service domain selection service indicator

摘要

A service indication mechanism is described for use by IP Multimedia Subsystem, IMS, codes (201, 204) of an IMS network (106) in routing a terminating call in a network comprising a circuit switched, CS, network (107) and an IMS network (105, 106). On receipt of a Service Initiation Protocol, SIP, message from a second IMS node (202), the SIP message including a called user number associated with the call (A1), a SIP Uniform Resource Identifier, URI, and the call services for the called user from a user profile database is retrieved (A2). A second SIP URI is generated by including a service indicator of the called user in the received SIP URI, the service indicator representing the call services of the called user (A3), the SIP message is transmitted with the second SIP-URI to a third IMS node (204). On receiving the transmitted SIP message, the third IMS node (204) detects whether the service indicator is included in the SIP URI, and applies the service indicator to a plurality of policy rules for indicating whether the terminating call should be routed to the CS network (107) and whether to suppress insertion of a prefix to a CS routing number of the called user. The third IMS node (204) transmits to a CS node (206) a SIP message including the CS routing number without the prefix when a routing policy rule associated with the service indicator indicates suppression of the prefix (B5).