Previously I had installed the Radio Shack Snap-on Ferrite Data-Line Filter part number 273-0105, snapped around the phone wire that comes out of the Ooma device phone port, to filter out “noise”.
With the filter is installed on our setup, DTMF tones are not heard on either end of the conversation.
Ooma had me remove the filter to do some testing. When the filter was removed, the DTMF tones returned.
When the filter was reinstalled, the DTMF tones are gone from our setup.
Shawn wrote:I want to report that the Radio Shack ferrite choke core filter did not work for me. My daughter indicated DTMF tone every time she spoke to my wife on our Ooma line. I have a much lower tone and she said I almost never trigger the DTMF tone. So I put the filter on the phone wire as close to the Telo unit as possible. My daughter called and spoke to my wife. After that, she indicated the DTMF tone was till there, if anything, it might have been a little more frequent than usual. Back to waiting for the bug fix.
In my case the filter probably de-tunes the audio circuits. In Shawn's case the filter probably tuned the audio circuits in the other directions. It probably would be just trial and error to find the correct value filter, to cancel the FTMF noise, for an individual user's setup.
Up to this time no one else has reported using the filter or any results.