DTMF Tone Problem

[msk20171]

I have a Galaxy S4 with Android 4.3.1/ CM 10.2.1. If I call a number that has IVR, the DTMF tones don't seem to work. I can hear the tone through the earpiece, but the IVR doesn't register it. This happens with numerous different numbers (bank, hotel, conference call), so I think the problem is at my end.

I can't find where to change the tone volume or length. Any assistance would be greatly appreciated.