Reuters, via Bell System Memorial, reports:

PHILADELPHIA, Sept 12 (Reuters) - AT&T Corp. (NYSE:T - news), the No. 1 U.S. long-distance telephone and cable television company, said its communications network carried a flood of heavy calling volume on Wednesday, but remained unharmed after its equipment survived the collapse of the World Trade Center.

Calling volume on “the network is running about about 20 percent above a typical Wednesday morning,'’ AT&T spokesman Dave Johnson said. “There’s heavy inbound surge to the New York and Washington areas and some network congestion, but nothing like yesterday.'’

AT&T handles about 300 million voice telephone calls a day. It carried 431 million calls on Tuesday as customers flooded the telephone lines in the wake of the attacks on the World Trade Center and Pentagon, making it the heaviest business day in the company’s network history, Johnson said.

AT&T’s local network switching equipment, which routes telephone calls, was located in the basement of the World Trade Center towers and survived the implosion of the buildings, Johnson said.

“It appears the equipment has survived … It was up and alive and still providing dial tone by 4 o’clock yesterday afternoon. Once the back-up batteries ran out, we took them offline, but the equipment is still working,'’ Johnson said.

“We were amazed,'’ he said. “It was several stories under ground and all I can say is that they must have built up that basement very sturdy.'’

The switching equipment handled calls for AT&T business customers in Lower Manhattan. The company rerouted calls and suffered no network outages, Johnson said.

AT&T will retrieve the equipment once it gets approval from New York City and disaster teams to approach the rubble of the World Trade Center. The New York-based company said none of its employees were injured or killed in the attacks.