An Internet protocol (IP) packet switching communication system using real time transport protocol (RTP). Control packets map group identification codes to a multicast address on a network. Control packets are distributed on the network using simple object access protocol (SOAP) messages with extensible markup language (XML) payloads. Mapping may include dynamic or static functions. Multicast address data is distributed among routers. A message from a caller is multicast by the routers, based on the multicast address, to one or more destinations.