Help with Twilio SIP - Fanvill phone - Grandstream HT-812 device for ax

[USCBigRed]

I am trying to setup a Grandstream HT-812 for use on a Twilio Trunk that i'm running on Fanvill phones.
I'm on version 20 and I can't find out how to make the Direct Dial Fax line get to the HT-812 via the fax setup.
Has anyone done this successfully or know any links that could help?
Thanks

 

[Charles_3CX]

Based on our testing via our interop team this is a supported provider but it is not tested/supported for fax