Grandstream HT801 FAX Issues

[healthy]

Konica Copier / FAX => Grandstream HT801 => Flowroute SIP Trunk
I have installed as per 3CX instructions, however I'm having the following issues:
I can outbound fax, can hear tones from communication, and successfully receive good quality faxes sent to our 3CX FAX Server.
Inbound faxes don't work, and what's more, it appears to chew up 6 inbound sessions. I will see in the call log multiple entries. Faxes never get to the machine because it takes over all the available inbound routes.
If I route the DID to the Fax server, I get a fax as expected.

Thanks for any help!

 

[Alejandro_3CX]

Hi @healthy fax is not listed as supported using flowroute sip trunks



if by any chance they support it then please feel free to enter in contact with them so you can configure the ATA with the correct FAX Transmission Mode



If fax in audio is used, then you may need to enable the parameter G.711 to T.38 Fallback from the fax server and restart the IVR Service, set a dedicated DID to the fax extension and use codec PCMU/PCMA as primary.

Have a great weekend!

 

[SweetAction]

FYI,
While officially not supported by 3CX, Flowroute does support fax via T.38 (https://flowroute.com/faxing/) and it does work in this configuration (Grandstream ATA -> 3CX -> Flowroute) for many of our customers.

The fact you have it working outbound AND inbound when using the 3CX fax server, but not inbound when using the ATA tells me something about the ATA might be wrong. Check your firmware (it can be a massive pain to get it past certain versions), factory reset and reprovision, and potentially open a ticket with Grandstream if a packet capture doesn't shed some light.

 

[healthy]

FYI,
While officially not supported by 3CX, Flowroute does support fax via T.38 (https://flowroute.com/faxing/)

Thank you, I did just get off the phone with FlowRoute and they said that they don't care what goes across their connections.
The Grandstream FW update went smoothly, but I'll re-visit and re-flash it.
Thanks again!