Touch tone replacement for internet telephony

摘要

Tones that are generated by a telephone or PC (such as DTMF tones) and subject to loss or noise during generation or during transmission along a medium are detected and replaced with substantially noise-free and distortionless digital signals. In one embodiment, the replacement of the tones is done in a modem embodied in an Internet telephony Gateway/Terminal, such as in a network access server coupling a time division multiplexed telephone line to a packet-switched network. The replacement of the tones may also be performed in any suitable device that provides an interface between a time division multiplexed transmission medium and a packet switched data network, such as in the modems of a cellular telephone network to Internet network access server.