It's common knowledge that calling traffic spikes during the following:
1) holidays
2) when there is a disaster
It is fully expected to have a call spike in Nashville.
If someone wanted to do major damage to AT&T they wouldn't attack Dallas or Atlanta (multiple buildings BTW in each city), but Tech Mahindra and Infosys in India and Mexico (Yes Mexico and that to bypass H1b limitations and US immigration law- lots of IT Indians in Mexico.) AT&T's key data centers are not in Atlanta or Dallas or anyplace on an outage map.
If anyone wanted to kick western civilization in the balls they would take out the data centers in Bangalor, Hyderbad "Hi Tech City", Delhi and Mumbai.
The Chink virus wasn't needed at all.