Patent ID: 7173944

Claim:
A modem for coupling directly to a subscriber line, the subscriber line providing a communication path for telephone equipment, the modem comprising: an on-hook/off-hook detector means for detecting whether the telephone equipment is in an in-use state or a not-in-use state, and to output an in-use/not-in-use signal indicative thereof; and a modulator means for receiving the in-use/not-in-use signal and to provide, based on the in-use/not-in-use signal, one of a plurality of types of modulations to signals that are transmitted by the modem, wherein, when the in-use/not-in-use signal indicates that the telephone equipment is in the not-in-use state, the modulator means provides an amplitude modulation to the signals that are transmitted by the modem, and wherein, when the in-use/not-in-use signal indicates that the telephone equipment is in the in-use state, the modulator means provides a shift key modulation to the signals that are transmitted by the modem.