Modems, methods, and computer program products for recovering from errors in a tone reversal sequence between two modems

Abstract

Modems, methods, and computer program products for recovering from errors during a tone reversal sequence between a modem pair detect a false tone reversal during a tone reversal sequence at a first modem. If a false tone reversal is detected, then the first modem requests that a second modem restart the tone reversal sequence. Tone reversal sequences are used, for example, in the startup protocols of both the V.34 and V.90 standards to calculate the round trip delay between two modems. Neither standard provides for any recovery procedure, however, should the tone reversal sequence fail. The modems, methods, and computer program products can allow errors in a tone reversal sequence to be addressed immediately rather than proceeding to later phases in the communication protocol where the errors may ultimately cause the communication session to breakdown.

Dependencies are inferred from the claim text.