[Freeswitch-dev] Detecting in-band DTMF Digits in Openzap?

For FXO I switch back to the dialtone state and collect the digits via the ZAP_SIGEVENT_COLLECTED_DIGIT call back (which is a little bit ugly and does not allow dial ahead, but it works). However, for the E1 PRI card there is no dialtone state, which makes sense as the digits are sent over the D-Channel ('VETO Changing state on 1:1 from UP to DIALTONE' is printed if you try). Openzap must be able to detect digits during a call, but I am having trouble figuring out how. ie. How do you use Openzap to detect in-band DTMF digits during a call? Thanks, -alex