Abstract: A Session Initiation Protocol Application Server for use within an IP Multimedia Subsystem. The Application Server comprises a receiving unit for receiving a Session Initiation Protocol message from a Serving Call Session Control Function, the Serving Call Session Control Function serving an IP Multimedia Subsystem user and the message containing within a message header an explicit identification of said user. A processing unit determines an action to be applied to said message and includes within a header of the message a role value defining a role of said user in respect of the action. A transmitter unit returns the message including the role value to said Serving Call Session Control Function.

Abstract: The invention provides a method of establishing communication in a communications network in which a communication initiation request including service suppression information indicating that the whole or part of a communication service associated with the communication should be suppressed is generated and sent to initiate communication. When the communication initiation request is received (50) it is determined (52) whether it includes service suppression information indicating that the whole or part of a communication service associated with the communication should be suppressed. If so, the whole or part of a communication service corresponding to the service suppression information is suppressed (54).