TELECOMMUNICATION SYSTEM WITH PACKET-SWITCHED-MULTIMEDIA-SESSION-TO-CIRCUIT-SWITCHED-CALL TRANSFERRAL

摘要

Telecommunication systems with packet-switched multimedia terminals and nodes for packet-switched multimedia sessions and with servers for exchanging multimedia signaling information for the packet-switched multimedia sessions and with terminating units are provided with gateways for in response to transferral messages originating from the packet-switched multimedia terminals and arriving at the servers transferring packet-switched multimedia sessions between packet-switched multimedia terminals and nodes to circuit-switched calls between gateways and circuit-switched terminals via switches, to continue possibly interrupted sessions via replacing calls. The servers send invitation messages to gateways, which send setup messages to switches for setting up circuit-switched calls via partly alternative communication paths. The servers send information messages to terminating units for bringing the terminating units from session level to call level. Preferably, a packet-switched multimedia terminal and a circuit-switched terminal are one and the same terminal.