Codec question

Probably a very simple question.... BUT....

I have been using trixbox for fax2email.
This worked PERFECTLY out of the box.

But ... now my DID supplier, has changed something on the lines.
So it stopped working.

Now he says that i must activate T38 support or else use G711u with a packetsize of 30 ms.

Can anyone translate that and tell me how to solve this problem?

And does this compromise the current use of the fax2email service?

Thank you for your assistance !