Signal q.931 and BCD encoded

I am connecting my * to a tandem switch with pri line. But my switch only can receive the q.931 receive frame signalling to terminate the call. After i pass the call to the switch i found out i receive the BCD Encoded type signalling. The signal type is not matching so i cannt terminate the call.
Can anybody tell me how to change the signalling to q.931?

i m using

switchtype =euroisdn
signalling = pri_cpe