ATA's Fax fail after 15 seconds SV9100 CP20 - Sundance Business VOIP Telephone Help

We recently upgraded a CP10 to CP20. There Cisco ATA's are registered back up on the SV9100 and we can make calls on them. But when we try and send a fax on any of them the Fax fails about 15 seconds into the fax. On the fax machines we have disabled ECM and changed the baud rate to 9600. The ATA's have been working for years just started having this problem after we upgraded to a CP20. Any thoughts?

Thanks

Was this a straight out upgrade or was your system re-programmed? Also, did the networking change at all. I mean IP addresses etc.

Just as a side note why use ATA's rather than an analog card on the SV?

It was a converted database. No network changes.

They have multiple locations and 1 SV9100 connected thru VPN.

What fax protocol do those ATA's use? You might need to put that back into the programming. There is some sort of fax and forward for ATA's if memory serves.

Maybe a good time to migrate from ancient Fax to modern day PDF.

Would be great save the fact that the alternative doesn't work for HIPAA. Anyone that works in first responder/medical/HR knows fax machines are going to be around another 100 years.

Yup exactly Coral the medical field is not getting rid of Fax machines..

Here you go Coral put this in your notes if you have this issue with a CP20. I did this and it worked.

Per NTAC:

If you have a site with SIP trunks doing faxing through a 3rd party SIP ATA and the faxes are failing but the 3rd party SIP voice calls are fine AND you are on a CP20

Disable 84-33-01 for SIP Trunks & SIP Extensions (Fax Relay Mode)

If you have this with a CP10, you:

Enable 84-33-01 for SIP Trunks & Extensions

Per NTAC, the CP20 processes SIP a bit differently than the CP10.

Though logically this makes no sense to me (in black and white -regarding the programming) this apparently is a well known thing for CP20.

That is so weird....like Panasonic confusing....

Yep... We had the exact same problem but with analog blades. Had a CP-10 for years no problems. Migrated to a CP-20 and problems with fax's. Called NTAC and they had us disable 84-33 Fax Relay for SIP trunks and all is well.