Abstract: In order to facilitate group communication using characteristics of a pre-arranged group but not involving all members of the pre-arranged group, a parameter indicating that the group communication is not intended to all members of the pre-arranged group is added by an inviting group member sending a request to a group server, and the group server, in response to the parameter, is configured to not to invite all members to the group communication.

Abstract: A solution for establishing a session of a real-time media communication service in a communication system comprising at least two separately administered subsystems. The session establishment comprises receiving a request for session initiation, querying subscriber information related to the requested session, and initiating the session according to the queried subscriber information. The invented method comprises detecting that the terminating subscriber does not belong to the same subsystem as the originating subscriber, determining a defined transit server associated with the terminating subscriber, said transit server having access to a subscriber database of the subsystem of the terminating subscriber, and querying subscriber information related to the requested session with a first control message comprising parameters of the requested session to the transit server.

Abstract: The invention relates to a protocol converter (14) and a method utilizing the converter, enabling a wireless connection (13) between a cellular network (11) and a terminal to apply a reduced RTP protocol according to the invention, instead of the RFC 1889 protocol, in order to save communications capacity on speech connections.