[Freeswitch-users] Dequeue DTMF from FreeTDM Channel

Hi all, I have a freeswitch configured with freetdm and wanpipe.My problem is with dtmf. When calling from an external pstn number to freeswitch, dtmf seems to be detected properly and enqueued it in the channel consistently. But when call came to same channel again, dtmf which is stored in the buffer for the previous call is used in the current call.So when i am done with previous call i want to dequeue the dtmf in the channel .So the problem seems to be something I've misconfigured with the Sangoma card. Can anyone point me in the right direction? Thanks, Subhash.