Did the phone and the ringer work before?
Have you tried it with just the phone hooked up and not the ringer?
Have you tried the phone hooked to the one that the fax machine is on to be sure that it isn't the ATA?

My guess is that the ATA doesn't have the umph to push a phone and a loud ringer. If you can get the phone to work you might then have to come up with a work around for the ringer.

The Cloud is just someone else's computer!