Suttle Radio Interference Filter

There are times when a radio broadcast can "couple" into a phone line and cause interference. You can sometimes even hear and understand speech from the AM, CB, or HAM station. Interference from and FM broadcast is more likely to be a constant white noise.

The coupling occurs when a particular stretch of telephone line is just the right length and orientation to capture the energy of a strong local broadcast at just the right frequency. In technical terms, the telephone wire becomes an antenna and the wavelength on the piece of cable is tuned to the strong local signal.

To correct this problem, you can replace the cable with twisted pair instead of straight cable, change the length considerably, reroute the cable to change its shape an orientation, or use shielded cable.

Or you can try this filter.

Used in place of a surface mounted jack assembly to eliminate AM/Fm and CB radio broadcast interference in phones caused by nearby transmitting antennae.