AT&T and T-Mobile share networks in storm-battered areas

On Tuesday, the Federal Communications Commission said that about 25 percent of cell towers in the path of Hurricane Sandy were out of service. On Wednesday, the FCC said the figure had fallen "a few percentage points."

Flooding, power outages and high winds can destroy or temporarily disable cell towers, leaving customers without wireless service.

"AT&T and T-Mobile customers will be able to place calls just as they normally would, but their calls will be carried by whichever network is most operational in their area," the companies said. "This will be seamless for AT&T and T-Mobile customers with no change to their current rate plans or service agreements even if the phone indicates the device is attached to the other carrier’s network."

Both AT&T and T-Mobile use GSM wireless technology, allowing them to share traffic between the two networks.

AT&T tried to buy T-Mobile for $39 billion last year, but regulators blocked the deal over concerns it would stifle competition in the wireless market. AT&T is the second largest carrier in the country, and T-Mobile is fourth.