Allworx Technical Support Forum

I have plugged a fax machine into the analog port on a 536. I can call out on the port. I checked the box that the port was connected to a fax machine. If I call in it answers with a fax tone. I tried changing the baud rate on the machine to 2400, 9600, 14400, and 33600. I get poor line quality on the report.

If this is over a SIP trunk then you're gonna have a bad time, most of the time. You may need to have the SIP trunk vendor set the CODEC to G.711U. If this is an analog line, bypass the Allworx entirely to see if that makes a difference. I can think of only one reason to connect a FAX with it's own dedicated line to the Allworx...to log the calls. Maybe if you want to use the FAX line for outbound voice calls but then the chance of that interfering with FAX is not worth it.
And if possible, try with a different FAX machine.

Can I assume that an ATA would be a better solution? I got that one to work somehow, but I have another fax machine on the same system that seems to time out after 25-30 seconds and return a fast busy. I hear the handshake but it doesn't connect. This machine is older. Adjusted Error correction to off and speed to slow and medium.

You cannot assume a different ATA will provide better results. The Allworx is acting as an ATA already. You can try a discrete ATA if you like but realistically it is time to consider FAX dead and move on already. As more and more phone companies themselves are eliminating analog dial tone it will become more difficult to have reliable FAX service though a phone line. There are innumberable eFAX type solutions available that are HIPPA compliant if that is a concern.
As always, make sure your Connect server is on the latest firmware which as of today is v9.1.12

In my experience ObiHai (Now Poly) ATAs were very reliable but you probably can't even find one to buy. So where old Cisco/Linsys but likewise you may not be able to find them. If you try a discrete ATA and stil have troubles you either need to consider the FAX machines themselves or blame the SIP trunking. Does your SIP trunk provider support FAX? Some do not.