Victims of Hurricane Katrina struggled to communicate with each other and the rest of the world yesterday, using everything from text messages to ham radio as most telephone service in New Orleans and coastal Mississippi remained devastated.

The near-blackout left outsiders desperate for news about loved ones, and in some cases created life-and-death situations as aid workers struggled to get information about people stranded by rising floodwaters in New Orleans.

Phone companies had trouble even comprehending the extent of damage to their systems because they could not get into some parts of the region. One telephone executive said the storm might have caused unprecedented damage to a communications infrastructure that people have come to take for granted.

BellSouth Corp., the dominant local telephone-service provider for the region, with a network that is also vital to wireless telephone systems, said as many as 1.75 million customers along the Gulf Coast may be without service. One reason the networks will be so difficult to restore is that damage to wireless towers and copper, coaxial and fiber-optic lines could be spread across an unusually wide section of the country, from the Florida Panhandle to Louisiana.

The loss of service left residents nearly as frantic for communications as for food and shelter.

Cellular South technician Bruce Utley said a man flagged down his pickup truck in battered Gulfport, Miss., and offered to pay cash to use his mobile phone.

"I told him to go ahead and use it," said Utley, who has spent the past two days hooking up generators to his company's wireless towers along the Mississippi Gulf Coast. "You can't take money for something like that."

Utley had reason to feel sympathy, having watched a 50-foot oak tree smash through the new roof on his Biloxi house at the height of the storm, destroying parts of his kitchen and living room and sending rain streaming down the walls.

His son, Jason, 18, found another way to communicate, using a text-messaging service that was sporadically available to contact a friend in Biloxi to find out if he had survived the storm.

"Water got to the ninth stair of my two-floor house, but everything's fine," he said the friend replied.

Some residents chronicled their experiences on Web logs, with news organizations compiling lists of such online journals on their Web sites. But power failures made it difficult to run computers or get Internet access and threatened to undermine phone service further.

"We have the dual challenge of dealing with the loss of commercial power, which is affecting our service, and of dealing with the actual physical damage to the network," said BellSouth spokesman Joe Chandler. The company had no estimate on when it would be able to restore all service, he said.

Mobile-phone providers said their service was severely limited, at best, in New Orleans and along the Mississippi coast, and they encouraged people to use text messages instead of making voice calls. Text messages are sent in small "packets" of data, using less bandwidth to get through overloaded lines more easily.

"Text messaging has been our savior right now," said Richard J. Deshotels of Hammond, La., as he shopped at a Home Depot yesterday in Shreveport, where he went to escape the hurricane.

Friends in Hammond were able to let him know that his house was spared, Deshotels said.

Ham radio operators told of people dialing random numbers from their weakening cell phones, hoping to get a signal and to reach anyone who could send word that they needed help.

On Monday morning, Sybil Hayes of Broken Arrow, Okla., got word by cell phone from relatives in New Orleans who said they were trapped in the second floor of their home, with the first floor filled with water. Their cell phone then died.

Hayes called the Red Cross in Tulsa, which put ham operator Ben Joplin to work. Joplin, part of a community of ham radio operators who mobilize during emergencies, was unable to reach any ham operators in the New Orleans area.

But he spoke to a fellow ham in Portland, Ore., who found another operator in Utah who was finally able to reach operators in Louisiana. The radio operators in Louisiana got word to emergency personnel, who rescued more than a dozen people in the house, including Hayes's 81-year-old aunt.

I was just so relieved," Hayes said.

Experts said it could be months before the full telecommunications network is restored, especially in New Orleans.

"This is the worst I have seen from an operations perspective," said Hossein Eslambolchi, chief technology officer of AT&T Corp. and a veteran of several natural disasters. "You almost have to rebuild the city. It may take an entire year."

Flooding also is damaging generators and the computer electronics that power telephone networks. Simply drying them out won't suffice. "If the water gets into the electronics, you can pretty much forget it," Eslambolchi said. They will need to be replaced.

One of the greatest problems for companies was just getting through to inspect damage in places like New Orleans, where police turned people away because of the danger from flooding and downed electrical lines.

Sprint Nextel Corp. said it was massing technicians, power generators and fuel in Baton Rouge, La., so they would be ready to roll when New Orleans is opened up.

Reed E. Hundt, a former chairman of the Federal Communications Commission, said the scale of the damage would make it hard to repair, and he bemoaned the government's failure to develop an emergency wireless network for rescue workers.

"We always discover the same thing," he said. "We need a national emergency communications network and we don't have one."

Staff writer Dana Hedgpeth contributed to this report from Louisiana.

Krystal Hurder tries to make a call with her cell phone yesterday as she and Edward Thomas wait for gas at a station in Gulfport, Miss.A worker at the Biloxi (Miss.) Regional Medical Center uses his mobile telephone. The center is one of three hospitals open in Biloxi.

Utility trucks leave for Birmingham, Ala., from Westwood, Mass., yesterday. Crews from New England will help repair the damage caused by Hurricane Katrina.