Patent ID: 8565291

Claim:
A communication apparatus for executing half-duplex data communication conforming to V.34 recommendation, transmitting an INFO 0c , sequence signal, and communicating with an answering communication apparatus that transmits an INFO 0a , sequence signal, a Tone A signal, a Tone A phase reversal signal, and an INFO h , sequence the communication apparatus comprising: a modulation-demodulation device to modulate and demodulate data conforming to V.34 recommendation; a control device to determine that the communication procedure shift to a recovery procedure by receiving the INFO 0a sequence signal transmitted from the answering communication apparatus again in a state in which the communication apparatus mistakenly detects the Tone A signal subsequently to the INFO 0a sequence signal for the Tone A phase reversal signal or the answering communication apparatus then cannot receive an initial INFO 0c sequence signal transmitted from the communication apparatus correctly, the control device to command the modulation-demodulation device to stop the recovery procedure when the communication apparatus receives the INFO 0a sequence signal while waiting to receive the INFO h , sequence signal even without receiving the INFO h sequence signal from the answering communication apparatus in the recovery procedure; and a circuit to receive the command from the control device through the modulation-demodulation device, and cause the communication procedure conforming to V.34 recommendation to return to a predetermined state in Phase 2 based on the command from the control device after the recovery procedure is stopped.