FreePBX and fax maxdatagram

Is there a way to set the maxdatagram for T38 through the FreePBX admin gui, or does that have to be done by editing the config files? If the latter, which config file should I put the entry in, and in where do I monitor the includes to make sure the modified gets included when asterisk loads?

I have the same question

I am guessing that the best way would be to add a custom field as mentioned in
but this feature request is wontfix but there is a similar request which says fixed but I only see the command in the sip settings page.