04972457 is referenced by 408 patents and cites 7 patents.

A laptop device includes a personal computer, a cellular transceiver, a speakerphone, and a hybrid communications control unit. The device has connectors for attaching a headset, cellular control unit, land telephone line, and additional speakers and microphones. The microprocessor-controlled hybrid communications control unit includes a modem, a data access arrangement, and a tone generator as well as digital, analog, and power switches. The hybrid communications control unit switches the communications components and provides, under program control, the proper protocols, level, and impedance matching to connect the modem, speakerphone, headset, speaker/microphone, or cellular control unit to the landline or to the cellular network via the transceiver. Matching and switching operations are automatic and transparent to the user. The unit can also connect two of the terminal devices or connect the cellular and landlines for call relaying. The device is capable of connecting plural calls at the same time. The hybrid communications control unit may be controlled by its internal firmware, by toggle switches, or by commands issued from the personal computer.

Title
Portable hybrid communication system and methods
Application Number
7/301521
Publication Number
4972457
Application Date
January 19, 1989
Publication Date
November 20, 1990
Inventor
Harry M O Sullivan
Red Oak
TX, US
Agent
Sixbey Friedman Leedom & Ferguson
Assignee
Spectrum Information Technologies
TX, US
IPC
H04M 11/00
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