We know that fax over PRI and SIP trunks is not 100% reliable.
We have been setting light-fax systems up this way for years without issues.
We have one location where inbound/outbound fax using SPA112 ATAs has been working without issue since Feb 2018. It worked fine on October 5. Since then it’s been very erratic; once in a while it works. Mostly it does not. Sometimes it connects and doesn’t negotiate. Sometimes it negotiates and sends some of the pages, then fails, etc. It’s erratic.
We have tried:
- Swapping out like SPA112s
- Downgrading SPA112 firmware
- Standing up a SIPStation trunk and routing faxes over it
- The above with T.38 enabled on the trunk
- A Grandstream HT-802 ATA
- Moving the ATAs from the wiring closet to the fax machines (to address possible cabling issues)
- Different fax machines (MFPs) in different physical locations in the office.
All modules up to date on Standard track
Comcast PRI with Digium G100 interface
SIPStation trunk with and without T.38 enabled
We aren’t seeing this sending or receiving with Fax Pro within FreePBX.
SIPStation support looked at packet traces and indicated that there is a protocol problem; a “not allowed” is being returned during the comms. I’ve requested the exact syntax of the error.
Again, this was problem-free until October 6. The only variable remaining seems to be FreePBX itself.
Any ideas? I’m about out of hair.
Edit to add: I registered the ATA directly to the SIPstation trunk and it works fine that way. Starting to look like some weird issue with FreePBX.