AT and T completed a record 430 million call completions on 9/11.

Transcript -- Call Gapping

What happens when one of the worst terrorist attacks in history strikes the densest cluster of networks on the planet? How did the largest communications provider in the United States handle the surge in demand? Despite surviving earthquakes, hurricanes and other man-made and natural disasters, the staff at AT and T struggled to cope with the flood of calls that followed the tragic events of September 11th. Over the course of the day they handled in excess of 400 million calls as people in America, and all over the world tried to contact friends and family in New York.  This collection gives a snapshot of how the communications company dealt with the unprecedented technological challenges by using techniques such as call gapping to help free up other services.