Applies to version(s): v2.6, v2.7
To enable T.38:
1. Select Profiles from the navigation menu.
2. Set Enable Fax/Modem Relay to enabled.
3. Set Detection Mode to Standard.
4. Set Relay Mode to T.38.
5. Uncheck the Use V.34 option. (For reliability reason, some faxes failed to failback to V17)