V20 Faxing Issues

[ebrownlee]

Since upgrading an instance to V20, we've had failures for faxes to come in both to the internal 3cx Fax server, as well as HT801 devices.

At first, I thought it was an issue with the HT801, and I removed and rebuilt the configs, updated firmware, etc to no avail.

When that didn't work, I ran packet captures on the on premise system, and I get 480 "Temporarily Unavailable" errors when the call goes to connect.

However, when calling to the fax extension, it connects fine.

This issue seems to be then on how 3cx is handling the incoming call on the trunk? Voice calls are fine, and switching the DID over to just a voice extension works fine as well.

No other changes have been made, but I'm at a loss now on where to troubleshoot as both the FXS device and internal fax server will not ring/answer from the outside.

 

[OlegR_3CX]

Hi there.
Are you using 3CX supported trunk, and what is it?
When you say you get 480 error, which party send this error, provider or a gateway?

 

[ebrownlee]

Source of the 480 is the 3cx server.

Flowroute is the truck provider.

 

[OlegR_3CX]

From what i can see, for the mentioned supported trunk FAX is not supported.
Do you see the number formatting is correct when you send the fax?
Maybe you can try and DM to the user here, as they did use mentioned trunk with FAX.

 

[ebrownlee]

Yes, formatting is correct, and this worked fine on v17 and v18, it’s only with the v20 upgrade that it has broken.

Also, T.38 is supported: https://flowroute.com/faxing/

 

[OlegR_3CX]

It has not been tested for FAX with 3CX interopt team, did you try recreating the trunk as new, or it simply uses the one you had on V18, just in case something has been changed in the template? Have you tried contacting the colleague from the link above?