I didn't see it mentioned previously that you have 2 ATAs. Make sure all the registrations are using different ports, or they can conflict and you'll get a variety of errors.

Try using each ATA separate, one at a time, to see if they can work by themselves, or if they are conflicting with each other.

Best solution would be to use a single voip device, with 2, 4, 8 lines, instead of 2 or more separate ATAs.

But if one works by itself, and the other doesn't, you may have a bad ATA.