Patent ID: 7411941

Claim:
A text telephone modem detection method for use by a first gateway, said first gateway being capable of communicating with a second gateway over a packet network, said method comprising: setting said first gateway to a voice mode having a first coding scheme; encoding an input signal using said first coding scheme to generate a first encoded input signal, while said first gateway is in said voice mode; transmitting said first encoded input signal to said second gateway over said packet network, while said first gateway is in said voice mode; looking for a first tone in said input signal while said first gateway is in said voice mode, wherein said first tone is indicative of a beginning of a text telephone modem character, and wherein said text telephone modem character comprises said first tone; detecting said first tone in said input signal while performing said looking; setting said first gateway from said voice mode to a text telephone modem mode in response to said detecting; providing a silence period, after a switching silence caused by said setting said first gateway from said voice mode to said text telephone modem mode, so as to prevent a detection of said first encoded input signal by said second gateway as said beginning of said text telephone modem character; and transmitting said input signal to said second gateway over said packet network, after said silence period, according to said text telephone modem mode.