Telephone line message waiting and ring indicator

Details Telephone line message waiting and ring indicator Telephone line message waiting and ring indicator

1991-12-19

1994-01-18

Dwyer, James L.

Telephonic communications

Supervisory or control line signaling

Signal reception at substation

379396, 379353, 379373, H04M 100

Patent

active

052805239

ABSTRACT:
A visual indicator circuit is provided for visually indicating that a telephone is ringing or that a message is waiting. The circuit includes a visual indicator such as a light emitting diode (LED), a voltage triggering circuit for triggering when a minimum predetermined voltage is applied to the telephone lines, and a current limiting circuit for limiting the current provided to the LED.

REFERENCES:
patent: 4648109 (1987-03-01), Boeckmann
patent: 4926459 (1990-05-01), Advani et al.
Sales promotion brochure ("Message Waiting/Incoming Call Indication Units") from Rummel Engineering Consulting.
"Phone Flasher Bypasses Message Feature", (Design Ideas), EDN, Dec. 20, 1990.

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