[Freeswitch-users] dtmf problem

Hello List, I have a freeswitch server with a digium tdm wildcard. Compiled, enabled, and configured freetdm and dahdi...all seems to be working fine (can make/receive calls). My problem is with dtmf. When calling from an external pstn number to freeswitch, dtmf seems to be detected properly and consistently. But when calling from a cell phone or via another voip line, dtmf doesn't seem to be detected, or detected only occasionally. On the same system, if I call into the voip number, calls from any of the three external options (landline, cell, sip) all seem to work fine with dtmf. So the problem seems to be something I've misconfigured with the tdm card. Can anyone point me in the right direction? Thank you, Tim