I have some problems with DTMF from a 3rd party PBX, when calling external. The 3rd party PBX needs in-band signaling. So, there's no SIP negotiation of DTMF over pots dial-peer and I don't understand if I should make another dial-peer for the incoming call leg on the CUBE, in which I should set the DTMF type.
3rd party PBX ---(SIP trunk)---> CUBE ---(ISDN)---> PSTN
Basically this is what I have configured:
voice dial-peer 1 pots
destination pattern 9T
forward digits all
I've followed some SIP traces, and basically the CUBE is not advertising any payload for DTMF, while the 3rd party phones are clearly advertising the required in band DTMF (101 payload)