A new ATA didn't fix it, and tech support has since confirmed that they 1) know it is affecting an undisclosed number of customers and 2) have no solution except power cycling/resetting the ATA when you discover no phone service (hopefully not when you need to call 911.) They are gathering information to try to figure out why they can't provide reliable service to customers.
Tech support also confirmed that they have no visibility into the modem stats or AT&T's network. This is shocking, as I can log into the modem I'm forced to rent and see that there have been no significant events since install. But Sonic can't see any of the vital statistics of the service they are selling? What support can they provide? Putting in a ticket at AT&T? Wouldn't it be more efficient for me just to buy U-verse?