Method for off-hook detection during ringing and the use of a su

Details Method for off-hook detection during ringing and the use of a su Method for off-hook detection during ringing and the use of a su

1995-01-20

1998-03-31

Zele, Krista

Telephonic communications

Supervisory or control line signaling

Using line or loop condition detection

379377, 379399, 379373, H04M 300

Patent

active

057347123

ABSTRACT:
A method and an apparatus for off-hook detection in a subscriber line interface circuit responds to a ringing signal which preferably lacks a DC component. A signal is generated that is a function of the line current through the subscriber line, and the time at which the signal exceeds a predetermined current value is measured. The measured time is compared with a predetermined time value, and an off-hook indication is produced in a processor depending on the comparison.

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