[asterisk-users] CHANNEL(t38passthrough) is 0

[Eric Wieling]

I'm trying to get T.38 passthrough working on Asterisk 1.8.18.1.  It isn't working.   Calls go through and are answered, but the fax machines are unable to communicate.   I checked the value of CHANNEL(t38passthrough) and it seems to always be 0.   One side is Level 3 T.38 TN and the other side is an Adtran NetVanta with POTS ports.   What would cause Asterisk to not offer t38 passthrough on a channel?