sundance-communications.com/forum Forums General General Telephone & Systems Information Radio Crosstalk

You could punch down a wire from unused terminal to unused terminal to a telco ground. You are dealing with a wire that could be 1/2 the length of the radio wave, or 1/4 or 1/8 or 1/16, etc. A wire half the length or one fourth the length, etc. is called a "harmonic" and the phone wire acts like an antenna.

You could probably bean on a tenth of the length, scatter it out in the ceiling and that would throw off the "harmonic" effect. nonameyet had the correct idea, you have to add an amount that removes the "harmonic" effect and that can be trial and error in terms of number of feet.

We had another such problem...at a customers office about an hour away...this was an intermittent problem, so of course, when we would get there, the problem would be gone.

We called Intertel...their story..."their phones don't do that"

In the end, we replaced the phones...and the radio was gone!

Another thing about my above example...a new person had moved to the desk...the previous person had never noticed the problem...go figure!

Sandman has an excellent troubleshooting flowchart for RF.
www.mikesandman.com
Here in Houston, I have found that most of my cases of RF were caused by the reciever cord, or the reciever itself. It's important to to try & ID if it is AM or FM you are getting so you can get the proper filter.