Interfacing data units to a telephone line

Details Interfacing data units to a telephone line Interfacing data units to a telephone line

1986-12-15

1988-11-01

George, Keith E.

Telephonic communications

Telephone line or system combined with diverse electrical...

Having transmission of a digital message signal over a...

379 93, 379355, H04M 1100

Patent

active

047825120

ABSTRACT:
The present invention provides an apparatus for selectively connecting one of a plurality of data units (21,22,23) (for example modems) to a telephone line (20). The apparatus comprises a plurality of interface circuits (24) each having a respective data unit connected thereto. Also connected to each interface unit, and thereby connecting the interface units together, is a common dialing device (28), a telephone line, a dial request bus and a line occupied bus. Each interface circuit has a dial connect switch and a line connect switch, a first switching means for connecting the telephone line to the common dialing device, on operation of the dial connect switch, and a second switching means for disconnecting the telephone line from the common dialing device and connecting the telephone line to a data unit on operation of the line connect switch. The interface circuit also includes processing means for supplying a dial request signal to the dial request bus, when the common dialing device is connected to the telephone line, and for supplying a line occupied signal to the line occupied bus when its respective data unit is connected to the telephone line.

REFERENCES:
patent: 3818449 (1974-06-01), Epstein
patent: 4125872 (1978-11-01), Maxwell
patent: 4130736 (1978-12-01), DeMarco et al.
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patent: 4482786 (1984-11-01), Flynn, Jr.
patent: 4485274 (1984-11-01), Jordon et al.
patent: 4513175 (1985-04-01), Smith
patent: 4645879 (1987-02-01), Simmons
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Bell Laboratories Record, vol. 54, No. 11 of Dec. 11, 1976.

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