US Patent 7286521 Localized voice over internet protocol communication

An approach to abstracting the circuit switched nature of the public switched telephone network (PSTN) by using VoIP to provide voice actuated services is disclosed. By carrying a telephone call using VoIP technology for a short distance (frequently within a server room) significant benefits to call handling and capacity management can be obtained. Specifically, a PSTN-to-IP gateway is used to receive (and place) calls over the PSTN and route those calls internally to servers over an IP network in a packet switched format. A number of computer systems can receive and handle the calls in the IP format, including: translating the packets into an audio format suitable for speech recognition and creating suitable packets from computer sound files for transmission back over the PSTN.