asterisk users - May 2018 - res_fax_spandsp - information about used protocol t38 or g711?

Hello!

I'm working on a fax solution, which reports the result of each sent or
received fax to the database.

When using option "F" or not using option "f", it's
clear which protocol
has been used. But if "f" is used, it could be g711 or t38. Is there
any
variable which contains this information at the end of the fax transmission?

I'm using asterisk 13.


Thanks for any hint,
Michael