Patent ID: 7158543
Filing Date: 2007-01-02
Classification: H04L,H04M

Abstract:
1. A system, comprising: a first modem configured to operate a predetermined high speed modulation, the first modem to initiate a call having a call path that extends from the first modem, over a circuit switched network to a first gateway, and then from the first gateway over a packet switched network to a second gateway that is not configured to operate the predetermined high speed modulation, and then from the second gateway over a same or another circuit switched network to a second modem that is configured to operate the predetermined high speed modulation; the first modem to initiate V.8bis signaling on the call path, the V.8bis signaling configured to elicit, from the second modem, a compatibility response indicating that the second modem is configured to operate the predetermined high speed modulation; the first gateway to intercept the V.8bis signaling before reaching the second gateway and before an answer tone is established for the call; the first gateway to determine that the intercepted V.8bis signaling is configured to elicit the compatibility response from the second modem when the V.8bis signaling includes a predetermined dual tone having a frequency of approximately 1375 Hz and 2002 Hz and a duration of approximately 285 ms to 400 ms; the first gateway to block the predetermined dual tone included in the V.8bis signaling to prevent the predetermined dual tone from reaching the second gateway and the second modem thereby disrupting V.8bis signaling negotiations between the modems to prevent the modems from operating according to the predetermined high speed modulation during the call; the second modem to receive configuration signaling that does not include the predetermined dual tone; the second modem to send a different response that indicates that the second modem operates according to a different modulation than the predetermined high speed modulation, the different response sent in response to receiving the configuration signaling that does not include the predetermined dual tone; and the first modem to operate according to the different modulation in response to receiving the different response and in response to the first gateway blocking the predetermined dual tone.