Packet-switched telephony with circuit-switched backup

Abstract

A packet voice switchand method for its operation are disclosed. The switch comprises a network switching means, preferably implemented within its host processor, that allows calls to be routed between a circuit-switched connection at circuit-switched interfaceand either another circuit-switched connection at interfaceor a packet-switched connection at packet-switched interface. The network switching means selects call routing for calls based on a comparison of the current quality of service for the call over the packet-switched connection vs. the extra cost of connecting the call over the circuit-switched connection. Preferably, the comparison can be adjusted for call distance, the user's own quality of service preference, and current system load. In a preferred embodiment, switchcommunicates with a similar packet voice switch (handling the other end of the same call) in order to initiate a mid-call network switch that is transparent to the calling and called parties. This embodiment provides a guaranteed minimum quality of service for packet voice applications, and provides a reliable backup in case of a packet data route failure. In a second embodiment, users may initiate network switching themselves if they desire higher quality, by entering an appropriate sequence on their DTMF keypad.