Method and apparatus for establishing communications between packet-switched and circuit-switched networks

Claim 1

In a process executing on a computer system operatively coupled to a packet-switched data network, a method for establishing communication between the process and a terminating apparatus on a circuit switched communication network, the packet switched data network being operatively coupled to the circuit switched communication network by one or more gateway apparatus, the gateway apparatus and executing process being addressable over the packet-switched data network through respective network protocol addresses, the terminating apparatus and gateway apparatus being accessible over the circuit switched communication network through respective telephone numbers having area code, exchange, and subscriber segments, each segment comprising a sequence of numbers, the method comprising: A. generating a telephone number domain name identifying a telephone number by reversing the order in which the segments of the telephone number were received without modifying the sequence of numbers within each segment; B. supplying the telephone number domain name to a domain name server operatively coupled to the packet switched network; C. receiving from the domain name server a network protocol address of a gateway operatively coupled to the packet switched network; D. supplying the telephone number domain name to the gateway indicated by the network protocol address; and E. establishing a real-time, point-to-point communication connection through the gateway with the terminating apparatus identified by the telephone number domain name.