Verizon said it can't estimate how much of a dent the storm will put in its operating profit "but we expect that it could be significant," CNN Money reported Friday.
The nation's largest wireless carrier said 96 percent of its towers in areas affected by the storm are operational but returning the other towers to service would require significant effort.
"Unfortunately, the extent of the storm damage -- including lingering power outages and inaccessible roadways -- in harder-hit areas like New Jersey and the New York City metro area makes full restoration a marathon and not a sprint," Bob Mudge, president of Verizon's consumer division, said in a statement. "We ask for customers' patience and understanding."
Verizon wasn't alone in being hobbled by the storm, with the Federal Communications Commission saying Thursday 19 percent of cellular sites in 158 counties across 10 states, from Virginia to Massachusetts, were non-operational.
Verizon said 97.2 percent of its cell sites in the area affected by Hurricane Sandy were back in working order Friday.
"Our coverage in most areas is approaching pre-storm status," Verizon said in a statement. "In severely impacted areas, such as Lower Manhattan, while wireless service has yet to return to normal levels, coverage is good."
Verizon, along with T-Mobile and AT&T, have indicated they will waive late fees on customers' accounts because of the disruptions caused by the storm.
ATM fees on the rise, again