Q.: Message waiting light ... how? [telecom]

For about a year, now, sporadically, our little ILEC-supplied, stand-alone, Caller-ID box has taken to flashing an amber "Message Waiting" light after an unanswered inbound call has stopped ringing. Rarely -- maybe once or twice a month. More usually it turns on a steady, green, "New Caller-ID info" light instead. (Same LED lamp for both lights -- a 2-color device.)

We have no ILEC-supplied voice mail, so there's no actual message awaiting us. And going off-hook long enough to hear 5-10 seconds worth of dial tone is enough to make that "Message Waiting" lamp turn off.

So, my question is: what sorts of signal on the line might be causing that lamp to light? or to extinguish?

TIA for any known facts.



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Look up the ADSI standard. There are specific tone signals to turn the message waiting light on and off.

R's, John

Reply to
John Levine

Thanks, John. Actually, ADSI is far too undisambiguated for Google to be much help. But [ ADSI Message Waiting Signal Standard ] brought up a Wikipedia article that may well have answered everything I was wondering:

: Some [stand-alone Caller-ID] units will also display the text "MESSAGE WAITING" : (similar to ADSI-compliant telephones). These units do not use visual FSK to activate : their red LEDs, but instead, they briefly "pick-up" the line at certain intervals (normally, : within two minutes of a new call) to check for a "stuttered" dial tone. The presence : of a stutter dial tone will activate a red LED; while absence will deactivate it.

... both what might cause it to go flashing when there's no voicemail service for it to be reporting about, and why 5-10 seconds worth of fresh dial-tone may bring that flashing to a halt.

Cheers, and thanks again, -- tlvp

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If this is a regular POTS line from the phone company, chances are the box is just going off hook and listening for a stutter dial tone, to indicate a message waiting, any time after the phone has been used. I have multiple phones with line-in-use indicators, and I see this happening all the time, where the line-in-use lights up a few seconds after I hang up, then goes out again after a couple of seconds. I figure it's one of the phones that has a "Message Waiting" light on it, checking to see if anyone called while I was on the phone.

If the dial tone is impure or there is some sort of noise going on during the check, your Caller-ID box might be fooled into thinking it's a voice mail indication. When you go off hook yourself, it assumes you've heard the stutter dial tone, so it can turn its light out now.

Of course, digital lines have a completely different way of doing this.

John C. Fowler, snipped-for-privacy@yahoo.com

Reply to
John C. Fowler

You and the Wikipedia article I quoted from in my response to John Levine support each other quite nicely, so I think I can safely take "stutter tone" and simple dial tone as the answers :-) .

Thank you! Cheers, -- tlvp

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