Hello,

I use Asterisk 13.1 with a SIP trunk with a provider

When transmitting or receiving a fax in T.38 through the trunk with the provider I always get this warning:

WARNING [8204]: udptl.c: 852 calculate_far_max_ifp: UDPTL (no tag): Can not calculate far_max_ifp before far_max_datagram has been set

After the warning begins exchanging packets UDPTL, but all with sequence number 0 or 256. The fax is not properly transmitted or received.

I configured the trunk as follow:

t38_udptl = yes t38_udptl_ec = redundancy t38_udptl_maxdatagram = 400

How can I fix the problem?

Thank You Marco