TELECOM Digest OnLine - Sorted: Re: On-Hook Signal

Re: On-Hook Signal

William Warren (
Tue, 30 May 2006 16:52:34 -0400 wrote:

> Anyone know exactly what the on-hook signal for a plain old telephone
> looks like in terms of voltages? The information on the web is real
> contradictory.


The on-hook DC voltage should measure between 42 and 55 volts,
depending on the CO type and the locality. This is the nominal -48
volt Central Office battery.

On-hook AC voltage will be present during ringing, and it will vary
widely depending on the number of ringers on the line, the cable
condition, and the type of central office. You can expect to see
anywhere from 30 to 120 volts AC.


William Warren

(Filter noise from my address for direct replies)

Post Followup Article Use your browser's quoting feature to quote article into reply
Go to Next message: Ron Kritzman: "Re: On-Hook Signal"
Go to Previous message: "Add Voicemail to Partner or Get Different System"
May be in reply to: "On-Hook Signal"
Next in thread: Ron Kritzman: "Re: On-Hook Signal"
TELECOM Digest: Home Page