A DSL filter should do an excellent job, knocking down the AM band by
at least 25 decibels.

Try plugging in a phone instead of the modem and listen carefully, with
and without the DSL filter. The DSL filter should make a huge
difference. If it helps, but you can still hear the radio station, put
a second DSL filter inline.

If the filter doesnt make much difference, then the audio detection is
happening somewhere else, perhaps in another phone or your phone entry
box signal limiters. Try unplugging the other phones one at a time and
see if that makes any difference.

If that doesnt find anything, you might have to put a dsl filter
BEFORE the entry box or AFTER the entry box.



Or as close to the computer as possible. I believe they should work fine
in either direction, so you could plug it right into the computer then
use a normal phone cord to the wall. The AM signal may be picked up
right there in the cord into the modem.