"We're still largely in assessment mode," Verizon Communications spokesman Alberto Canal said. In Lower Manhattan, "We can't get in there to do work until the power companies do their work. ... It's still very early," he said.

Sandy affected Sprint Nextel service mostly in the New York tri-state area (New York, Connecticut and New Jersey) and in Pennsylvania and parts of New England, spokeswoman Crystal Davis said. Flooding, debris, and failure of commercial power and the wired links to cell sites were major causes of outages, she said.

"Some of our strike-team crews are out, and they are working to restore service where they can get access," Davis said. "Right now, it's basically a safety and an access issue."

Sandy has affected most of the East Coast, all the way from North Carolina north to Maine and Canada. Service in some areas may be restored more quickly than those in the band hit hardest by the storm.

"Every area has different impacts and different damage, so it's too early for us to tell when we're going to have everything up and running for every part of the country that's been affected," Sprint's Davis said.