Patent ID: 7151770

Claim:
A method of operating a communications system comprising a packet-switched network, a circuit-switched network, a plurality of gateways connecting the circuit-switched network to the packet-switched network, said method comprising: a) receiving packet traffic at one of the gateways; b) establishing in the circuit-switched network a circuit from said one gateway to a node on the circuit-switched network; c) outputting the said packet traffic from said one gateway onto the circuit of the circuit-switched network; d) concurrent with the outputting of said packet traffic in step (c), outputting, from a plurality of gateways, polling messages addressed to the destination address of the packet traffic; e) receiving at the gateways replies from the destination address; f) determining respective delays for the replies at different gateways; g) selecting one of the gateways depending on the respective delay times; and h) establishing a virtual circuit to the gateway selected in step (g).