Patent ID: 8380253

Claim:
A method of preventing acoustic echo in a two-way voice communication end device, the method comprising: upon starting a communication session with another communication end device, operating in a full duplex voice communication with acoustic echo cancellation mode; performing at least one quality check; determining whether the voice communication with the other communication end device has sufficient quality for effective acoustic echo cancellation; and in the event that the voice communication is determined to lack sufficient quality, operating in a tri-state voice switching mode; wherein operating in the tri-state voice switching mode comprises: operating in an outgoing state when voice activity is detected on an outgoing channel; operating in incoming state when voice activity is detected on an incoming channel; operating in a bi-directional state when voice activity ceases for over a threshold period of time while in the incoming or outgoing states; from the incoming state, forcing a transition to the outgoing state when there is voice activity on both the incoming and outgoing channels, but a first energy level associated with the volume of the voice activity on outgoing channel exceeds a second energy level associated with the volume of the voice activity on the incoming channel by a predetermined amount.