US Patent 7808981 Packet telephony across the public switched telephone network

A network device that allows packet relay across a public switched telephone network. The network device has a converter operable to convert a packet data stream to a public switched telephone network data stream. The converter may be a voice codec or a modem, as examples. The network device also includes a controller that can send signals in the public switched telephone network data stream identifying the network device as a packet device, receive signals indicating at least one other network devices are participating in a public switched transmission session with the network device, and then send the packet data stream across the public switched transmission network directly to the at least one other network device.