Automatic subscriber interrogation system

Details Automatic subscriber interrogation system Automatic subscriber interrogation system

1977-04-14

1978-04-04

Stellar, George G.

Communications: electrical

Land vehicle alarms or indicators

Internal alarm or indicator responsive to a condition of the...

340151, H04M 1100, H04Q 912

Patent

active

040829219

ABSTRACT:
The computer at the central office is connected to the automatic answering system either with or without ringing the subscriber's telephone. Tones sent by the computer to the subscriber system are filtered and compared to a reference signal and a connect signal is furnished when the comparator outputs indicate that the tones signifying the particular billing system have been received. The connect signal energizes a relay which connects the billing system to the telephone line. A holding circuit for the relay is also energized. A first time delay circuit furnishes a signal to start data transmission from the billing system to the computer a short time after receipt of the connect signal. A billing system furnishes an "access complete" signal deenergizing the holding circuit when billing data transmission is complete. To prevent voice signals from activating the comparators, an untuned differential amplifier has an input connected to the telephone line and furnishes a variable reference signal to the tone comparators, the output of the differential amplifier being less than the output of the filters when the correct tones are received and exceeding the output of the filters upon receipt of voice signals.

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