The present invention relates to a composite user agent acting on behalf of a group of member user agents in a communication network. The composite user agent provides its group of member user agents with a specialized proxy function while representing the group to the network as a single user agent. To devices on the communication network, the composite user agent behaves and is viewed as a user agent. To the group of member user agents, the composite user agent behaves and is viewed as both a registrar and a proxy server.