Why is pressing touch tone keypad not transmitted during calls? Recently, my wife's phone started acting weird in that when connected in a phone call, pressing the touch tone keypad is not working.  You can hear the tone being pressed in the speaker, but the other end of the phone call is not getting the tone transmitted.

What might be causing this and how could I go about getting this fixed?  She is running CyanogenMod7 on her HTC Incredible.
I got this to work under CM 11 by opening the Phone app, hitting the dotted line for settings, then un-checking the "Dial pad touch tones" option. I can't hear the touch tones anymore, but at least I can access my voicemail.

I have an international i9300.