atcomsystems.ca/forum Forums TDM Business Telephone Systems NEC Telephones & Systems SV9100 Intermittent static over idle phones

NEC SV9100 phone system has been installed for a year. Replaced a Toshiba that was old but no issues. The phones are all digital and the lines are analog from Comcast. The customer has complained from day one about intermittent static coming across the phones intermittently. It could be a day or a week. It is a burst of static across an idle phone’s speaker. It appears to be all phones. It happens any time of day and has happened after hours when only the customer contact was there.
Power was isolated on a dual conversion battery backup and the system was grounded as it previously was not. All parts have been replaced 1 by one including the 19” chassis and main cpu. None of this has fixed the issue. All the original parts are back in. NEC thinks it is noise coming in on the cables. I have eliminated 5 of the 20+ phones but the issue continues. I would hate to have to rewire and find out that isn’t the problem.
Any ideas?

I'm not at all familiar with NEC but back in the Nortel days my guess would have been Background Music. Sometimes when a defunct or de-tuned radio was connected to the MOH port it would cause a burst of static from time to time. Any users with BGM turned on would have heard it...

I think some old Iwatsu systems had a similar option. An audio source (in a case I saw, the paging system's background music) could be heard through speakers of idle phones set by a code on the keypad. I recall a service call years ago where the customer reported 'inference' from the local nearby radio station. I've seen that with powerful AM stations, but it was a setting on a few phones to play the background music source at a low level that was of the local radio station.

If in fact the NEC system (I'm not familiar either) has that option, maybe place a short across the BGM input.

NECs do have a background music feature and this was my first though too. On the SV9100 the default feature code to toggle bgm on and off is 725. Go to a phone and dial 725 and see if the display then reads BGM Off. If it does, then you know that it somehow got turned on. If it says BGM On, then it was off and you just turned it on so dial 725 again to make sure it's off and continue troubleshooting.

Since you have been in contact with NEC I'm sure BGM has been ruled out, by default it's disabled.
I have never had this issue with any NEC system in the past, this is a head scratcher.
By the way, one of the replies to this post said 725 might be a BGM feature code, it is not, by default this number is not in use but can be assigned if needed.

Dans I think it was a feature that was programmed in earlier Aspire, UX systems. If this is an upgraded system it could be like 825.

Thanks for the info Coral