New York City may be the top market for cell phone carriers, but it also has a uniquely complicated infrastructure. That made some aspects of the recovery from Superstorm Sandy more difficult, Randall Stephenson, chief executive of Dallas-based AT&T, told business leaders Thursday at the Penn Club in Midtown. Mr. Stephenson began his remarks at an Association for a Better New York breakfast with a synopsis of the transformations brought about by the release of the iPhone in 2007—and the unique challenges of serving millions of data-hungry users in a location with "the highest skyline and greatest vertical density population" of any city in the country. New York's high-rise living has also made its cellular infrastructure—and its crucial link to commercial power—harder to protect from disasters than those in other locations. Mr. Stephenson noted that in hurricane-prone areas like the Gulf Coast, cell phone towers generally sit on the ground, and have backup generators next to them. In New York, most antennas sit on rooftops—no place for generators. "I don't think many of you or many of your landlords are too enthusiastic about us having 200 gallons of fuel sitting on top of your buildings to fire up backup generators," Mr. Stephenson told the audience. "It's a unique challenge, to say the least." He praised his telecom industry peers for working together after the storm, and said that AT&T's cellular operations in the New York area were "pretty much back to normal" after Sandy. But as for safeguarding against future communications failures, he insisted there was "only so much you can do" when there's no commercial power. He added that he would be speaking to the chairman of the Federal Communications Commission, Julius Genachowski, later on Thursday, about protecting the communications infrastructure from future disasters, and that his message to him would be that private industry can't do it all. "Let's step up now and begin to ask what do we do about the electric grid," Mr. Stephenson said.