Installed FreePBX 16 distro. Added a couple of inbound routes and outbound routes.
In trunks → advanced, one can set UDPTL options. Once the fields have been populated and saved followed by apply, /etc/asterisk/udptl.conf contents are commented out. /etc/asterisk/udptl_custom.conf is empty.
So I am wondering what the results are and how effective the settings for UDPTL in the trunk advanced settings. What I did to be sure faxing works was to populate udptl_custom.conf.