MaltMan1

the phones have a backround humm when there is nobody speaking. the phone company was clean to the handoff. Anyone have any ideas what that could be resulting from? It's on all phones on all lines.

cathodekid

Hum is longitudinal imbalance. Somewhere there are pairs of copper that are within a short distance of a source of EMI. Three possibilities come to mind:

1) Some CAT-3-or-less twisted pairs have gotten mashed or otherwise untwisted within a short distance (12" or less) of an AC power line.

2) An existing AC Power line that's near the trunks is suddenly carrying much more current and thus producing more EMI. Did something like an air conditioner, heater or vending machine get installed in the area recently?

3) AC power supply hum in the switch itself. Does the incoming feed sound clean at the demarc on a butt set? If it does, it could be the switch.

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CK

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MaltMan1

putting a butt set on the DMARC is clean as a whistle. Go upstairs to use a phone and there's a humm

TouchToneTommy

It may not be "humm", but the data "ticking" bleeding into the audio. If you're using long line cords, expecially with the older modules and phones.

Plug your phone directly into the control unit, using a 7 or 14 foot line cord, and listen for the hum or noise. If it is clear there, then move one step at a time towards the actual jack. If there are cross connect terminals, pull the jumpers and try there again.

Finally, if you need a long line cord, use a Cat-5 patch cord (twisted pair). The phone's jack is 8-pin, you may need to replace the station jack if it is a 6 pin.

cathodekid

Good advice, TouchToneTommy.

If the switch is pretty old, I'm wondering if the electrolytic caps in the system's power supply are starting to fade.

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CK

avayaconsultant

I have seen a "soon to be failing" processor cause thi sas well.

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