There's an interesting blog maintained by an employee of a New Orleans ISP who stayed at their center, located in the CBD, throughout the disaster and kept it running.
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I don't know New Orleans geography, but it sounds like he must have been close to the BellSouth "main" facility on Poydras, as he mentions it at least once
On Thursday Sep 1 he says
We've got a prayer! Huge convoy of fuel and generator engineer types affiliated with Bell South just moved down the street toward their building. That's where 2 of our OC3s that went down are at Bell's main.