Cisco Technology, Inc.

Chieh-Wen Tsai

Herbert Michael Wildfeuer

Mehryar Khalili Garakani

Gavin Jin

In one embodiment, one or more gateways sniff the voice channel during the voice mode. If it is determined that V.8bis signals are being initiated, then the gateway breaks these exchanges by suppressing such signaling. Modem relay communications then are allowed to proceed. Briefly, the method and apparatus involve monitoring a call during a voice mode phase for an initiating signal representative of the defined signaling, the monitoring being performed by a local gateway and, if such an initiating signal is detected during the monitoring, then suppressing such detected signaling in such manner that the signaling does not reach the remote gateway. Preferably, the monitoring is for an initiating signal characterized by a dual tone of defined frequency and duration of approximately 1375 Hz and 2002 Hz for a duration of approximately 400 ms or 285 ms, in agreement with the ITU-T Recommendation V.8bis (standard) adopted by the International Telecommunication Union. Monitoring is continued at least until an answer back from an answering station is received by the gateway. When the suppression succeeds and the remote (non-initiating gateway that may be awaiting such an initiating signal halts any further V.8bis transaction attempts, the local gateway initiates a modem relay session of operation with the remote gateway.

Suppressing high speed modulation negotiation

The invented method involves one or more gateways sniffing the voice channel during the voice mode. If it is determined that V.8bis signals are being initiated, then the gateway breaks these exchanges by suppressing such signaling, thereby avoiding the above-described detrimental effects. Modem relay communications then are allowed to proceed. Briefly, the method and apparatus involve monitoring a call during a voice mode phase for an initiating signal representative of the defined signaling, the monitoring being performed by a local gateway and, if such an initiating signal is detected during the monitoring, then suppressing such detected signaling in such manner that the signaling does not reach the remote gateway. Preferably, the monitoring is for an initiating signal characterized by a dual tone of defined frequency and duration of approximately 1375 Hz and 2002 Hz for a duration of approximately 400 ms or 285 ms, in agreement with the ITU-T Recommendation V.8bis (standard) adopted by the International Telecommunication Union. Monitoring is continued at least until an answer back from an answering station is received by the gateway. When the suppression succeeds and the remote (non-initiating gateway that may be awaiting such an initiating signal halts any further V.8bis transaction attempts, the local gateway initiates a modem relay session of operation with the remote gateway.

V.8bis suppression method and apparatus for modem relay

A device is provided for coupling between a telephone line and the network, to exchange data between them. The invention includes software for the device, and methods of operation. The device detects when, in a fax/modem type transmission, the transmitted data encode silence or voice. This determines the end of the fax/modem type transmission, and then the device is switched to a more economical voice mode. The device analyzes the energy of the encoded signals. The device makes a discrimination of the type of signals (fax/modem, silence or voice) based on the time patterns of the energy. For fax/modem the pattern is relatively uniform, for silence it is uniformly low, and for voice the pattern oscillates.

Growing community of inventors

Santa Barbara, CA, United States of America

Chieh-Wen Tsai