T.38 passthrough Asterisk v10

I’m trying to enable T.38 passthrough for Asterisk v10… In sip.conf I added the below and I also made sure the udptl.conf file is correct. What else do I need to do?

t38pt_udptl=yes,fec,maxdatagram=400

I also tried

t38pt_udptl=yes

I just can’t get T.38 to passthrough…

Try to post some cli logs with SIP messages.