SPA941 and Asterisk 1.4.19 w. DTMF Issues

[jantypas]

I'm running Asterisk 1.4.19.1, and several ATA devices. I also have a SPA941 phone. That seems to be the problem.

Asterisk has dtmfmode set to rfc2833 for all, and has rfc2833compensate set to yes. All ATAs and the 941 can make outbound calls and can send DTMF tones correctly. However, if I call IN to the server via one of my DIDs form my cellphone, things get a bit strange.

If I dial in and just dial the SPA941 extension, when I hit DTMF tones on the cellphone, I can hear them on the SPA side.
If however, I set up a Followme to the same phone, when I dial in, the SPA rings, I answer and get the recording. (Press 1 to answer, ....) No matter what I hit on the SPA, now the digits are not heard by the Asterisk server.

The same problem happens if Grand Central forwards calls via the sama DID. I answer the call, but I can't send DTMF tones back. Yet, if I dial out, DTMF tones work.

What the heck is going on?