Sounds like this particular service is at&t's version of Verizon FiOS.
I had FiOS installed at the house soon after Verizon began selling it in our town. Been a happy customer for years. Very few problems. When a problem does occur, Verizon has been good about getting it resolved in, what I would consider, a reasonable amount of time.
The weak spot is the battery backup system for the ONT. The battery needs to be replaced every-so-often. I've had to have the battery charging unit replaced multiple times over the years as they do eventually malfunction.
No compatibility issues with my Avaya Partner ACS or any of our computer equipment.
