Call denial circuit

Details Call denial circuit Call denial circuit

1975-10-23

1976-12-07

Cooper, William C.

H04M 166

Patent

active

039964256

ABSTRACT:
A cail denial circuit is disclosed for restricting selected calls outgoing from a PBX or key telephone system. The circuit is arranged to handle both dial pulse signaling and multifrequency tone signaling from the same station while at the same time being arranged to prevent a mixture of the two types of signaling on the same call. One dial pulse detector is utilized for each line in conjunction with a multifrequency tone detector shared by all of the lines. A continuously operating scanner sequentially causes the registered digits, both from the individual dial pulse detectors and from the common tone detector, to be supplied to a common check circuit on a time-shared basis.

REFERENCES:
patent: 3821485 (1974-06-01), Harrington et al.

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