Topic: Phantom FAX Tone

[DaveR1]

Comdial DSII and KeyVoice system.

Dedicated FAX line was discontinued and no fax on the line anywhere (existing fax physically disconnected from the wall).
Normally, calls come in and the KeyVoice answers and distributes the call - no problem.
However, every so often calls are answered by a FAX tone - but NO FAX !

I can trick it every time by doing the following:
Call, get KeyVoice.
Hang up.
Call back.
Phone is answered with a FAX tone

Any suggestions as to where the FAX tone is coming from?
Again, no fax anywhere in the system, and I can't find any menu option that controls this.
Help !

[Skip555]

I would be looking for a alarm panel security or fire 

"fax tone " = modem answering

[Markk]

yup Skip is right. The modem in the alarm systems are set to pick up after so many programmed rings, sometimes they add rings from multiple calls and answer when the ring count hits the magic number. I have had a hell of a time trying to get alarm techs to believe me. Good Luck!
Mark

[DaveR1]

Interesting.  I would not have thought of that.  I don't think it's a "magic number" tho, I can make it happen every time I call immediately after a call disconnect.  Will check out the alarm company anyway - worth a shot.
Any other suggestions?

UPDATE: Spoke with the alarm company.  You are correct!  They are going to reprogram the alarm. Never would have thought of it as the culprit.  Thanks for your help

Dave

[telemarv]

That's how an alarm panel works. Call, hang up, call back, alarm modem answers.

[MnDave]

Also, fax tones (CNG) have a continuing interrupted chirp while a modem has a steady and slightly higher frequency after an initial connect chirp

[MacGyver]

The alarm makes sense.  Contact the monitoring station, go on test, disconnect the alarm (if you have one) and then try your routine again.

One other possibility is that there is a bad splice and the wire pair is a multiple going to another location.  You'll need to physically follow the activce pair when you call in to follow that one.  On the off chance that it is a fax machine, have you tried sending a fax to it with a note asking for a call back?

You can also call the modem from a terminal and get the answer string from the modem.  That might give you some insight.