Hello, Im having trouble with this configuration with sangoma A400 card. What happens is this : the call is established (bridged from FXS to FXO) to an IVR, then the caller press some key. At that moment, the sangoma card detects the DTMF on the FXS channel, and queue the DTMF to be sent of the FXO channel. As a result, to the remote IVR, the DTMF is received twice (once inband, and a second time when generated from the FXO). I sometimes get an even worse scenario where the DTMF is detected by the card on both channels, and an endless loop start as the DTMF gets detected by the other channel when generated and so on and so forth. I tried to stop DTMF generation by adding the following lines to the dialplan before the bridge <action application="stop_dtmf" data=""/> <action application="stop_dtmf_generate" data=""/> <action application="bridge" data="openzap/2/2/$1"/> But this did not help. I could kindof solve the endless loop by modifying zap_io.c in zap_channel_set_state, when the new state is dialing (which means the FXO channel is an outbound one, and I therefore dont need DTMF detection) I do a zap_clear_flag(zchan, ZAP_CHANNEL_DTMF_DETECT); which prevent further DTMF detection on that channel. I dont know where to carry on now, as just preventing DTMF generation on outbound FXO channel would prevent DTMF generation where A leg is sofia or any other. François