Call establishment for simultaneous analog and digital communications
AssigneeAT&T IPM Corp.
InventorsJoseph Q. Chapman, Kurt E. Holmquist
Life of this patent
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Abstract
A modem, capable of simultaneously coupling voice and data signals, connects local digital terminal equipment (DTE) and a local telephone to a communications link. To prevent the local DTE from responding to a communications containing only voice signals, the local DTE is notified of an incoming communication only after detection of calling tone signals on the communications link. Such signals indicate a remote DTE desires to establish a data communications path with the local DTE. This operation advantageously prevents the modem from transmitting an annoying answer tone to a calling party.
Claims11
Apparatus for use with first data terminal equipment deposited at a first end of a communications link, said apparatus comprising:
- a port for connecting to said communications link;
- switch means connected to said port;
- a hybrid coupled to said switch means;
- a modulator/demodulator coupled to said hybrid;
- first means for coupling to said hybrid, through said modulator/demodulator, a communication device, which communication device has an "off-hook" signaling means;
- and
- second means for coupling said "off-hook" signaling means to said switch means.
Dependencies are inferred from the claim text.