Patent ID: 6940846

Claim:
A telephony system in which a call can be handed off from a packet-based network to a circuit-switched network when the call invokes a feature that is supported by the circuit-switched network but is not implemented on the packet-based network, the system comprising: a circuit switched network switch that routes the call onto a first voice trunk and transmits an initial address message associated with the call; a first packet voice gateway, which sets up a connection between the first voice trunk and the packet-based network; a first connection gateway that receives the initial address message; a feature server that receives the initial address message forwarded from the first connection gateway, and conveys a routing message to a second connection gateway if the invoked feature cannot be provided by the feature server; the second connection gateway that selects a second trunk onto which the call is routed, which second trunk is in a shared trunk group connected to a second circuit switched network switch; a second packet voice gateway that sets up a connection between the packet based network and the second trunk; the second circuit-switched network switch that is connected to the circuit-switched network, which second circuit-switched network switch receives the call via the second trunk and provides the feature invoked by the call; and the routing message from the feature server to the second connection gateway including a trunk selection parameter, which parameter is determined by the type of feature invoked by the call, and where the second connection gateway selects the second trunk based upon the trunk selection parameter.