New Setup: Faxing can send out but not receive. (fax tones heard)

[TownTech]

I have a client that I setup a Grandstream HT001 for his fax machine. I can send faxes out to other fax machines and the faxes come through with no issues.
When I try to fax to the Grandstream HT001 to receive from another fax, I can hear the faxing tones come in, but then get a long solid tone and the fax fails.
Link to video with sound -> https://photos.app.goo.gl/QRxvBgL57xZ2mzTt5

 

[Guillaume Bourgeois]

Are you using a fax extension?
https://www.3cx.com/docs/manual/fax-server/

Does your SIP provider support T.38?

You wrote "Grandstream HT001"—did you mean "HT801"?
Is it running the latest firmware available on the Grandstream website?

Have you followed these instructions?
https://www.3cx.com/voip-gateways/grandstream-ht-fxs/

 

[TownTech]

Thanks for your quick reply. I am using Telin and I have submitted a ticket asking if they support it.
Also, yes I meant HT801 and it is running latest firmware.
Those instructions look outdated. I am on V20. But, yes, I have it setup like that.
Telin replied in their ticket: No our voice lines do not support t38, you could try enabling bypass.

 

[Guillaume Bourgeois]

Thanks for your quick reply. I am using Telin and I have submitted a ticket asking if they support it.
Also, yes I meant HT801 and it is running latest firmware.
Those instructions look outdated. I am on V20. But, yes, I have it setup like that.
Telin replied in their ticket: No our voice lines do not support t38, you could try enabling bypass.

I recommend trying to configure your FXS with a standard extension (not a FAX extension). Therefore, set it up as a normal extension. Select "Fax in Audio G711 (Pass Through)" under users TAB, and choose a non-FAX extension.



This should yield a good result.

 

[TownTech]

Still same result, but this time it makes the tone, then goes silent for a while.
Under the user, do I check "PBX delvers audio"? And uder SRTP it is currently disabled.
Call Forwarding, shows 20 second timeout before calls goto voicemail. Nothing is under IP Phone for that user, The view area has check mark on "Show My Calls" and "Presence" only.
Not sure if at this point I should switch away from Telin SIP and go with Voxtelsys SIP

 

[TownTech]

Anyone have any ideas?

 

[Guillaume Bourgeois]

Anyone have any ideas?

At this point, if it still doesn't work and Telin can't assist you, yes, I would suggest switching to Voxtelsys. They support T38, which increases reliability.

I don't like advising clients to switch from one 3CX-supported provider to another (also 3CX-supported), but if Telin can't help you, I understand the need to switch to ensure functionality, despite all the respect I have for Telin.

https://www.3cx.com/partners/sip-trunks/usa/