Wireless voice and data communication is the latest high-tech service cruise lines have embraced. Computer centers with Internet access already are common on most ships. Newer Wi-Fi connectivity, allowing vacationers to access the Internet with their laptops without plugging into a dataport, is spreading from designated hot spots to all parts of the ship, including cabins.

About a dozen lines now have wireless service on some ships.

Notable holdouts: Cunard, Princess Cruises and Seabourn. Cunard and Princess are considering it. Seabourn has not had "a hue and cry from our guests requesting this service," says Bruce Good, director of public relations.

But other cruise lines are promoting cellular service as an amenity that many of today's travelers expect. A July survey of 1,071 adults by International Communications Research for Cingular Wireless showed that a quarter of the respondents used their cellphone when traveling outside the United States. They averaged 10 calls per trip, most of them personal.

But not everyone welcomes the idea of hearing those ring tones and one-way conversations.

"I don't think [cellphones] belong on cruise ships," says Cheryl Tokarski of Philadelphia, a member of Cruise Critic, an online network of cruise enthusiasts. "I fear we'll be in the dining room, and everyone's on cells talking, but they have nothing to say: `Yep, we're on a cruise. We're eating dinner,'" she says. "Once I go on vacation, I'm on vacation."

Anne Goyer, a Cruise Critic follower in Sarasota, Fla., says she's drawn to sea travel "to totally escape the hectic pace and constant contact of the real world." She resists using computers aboard ship. "The advent of cellphones on cruise ships, in my opinion, will significantly impact cruising as we know it and certainly not for the better," she says.

Cruise lines walk a fine line between passengers who want to disconnect from the real world and those who won't go on a vacation unless they can stay connected to it.

"Travelers should have the option of choosing just how connected they'd like to be with the outside world while on vacation," Terry L. Dale, president of the Cruise Lines International Association, said in a statement. CLIA is a marketing organization for 19 North American lines.

"There's clearly an unmet demand," says Leighton Carroll, vice president of Cingular Wireless, which has teamed up with Maritime Telecommunications Network to form Wireless Maritime Services.

WMS and SeaMobile are two major providers of the wireless technology on cruise ships. The service works with most late-model wireless devices.

Guests can make and receive calls - and send pictures or text messages - as they do on land. But the service works only when a ship is offshore, Carroll says, because the provider companies don't want to interfere with local laws or compete with local shore service

Passengers are billed by their home cellular carrier at international roaming rates and don't have to pay extra to use the phone onboard.

Costs are $1.99 to $4.99 a minute, according to an association survey. Carroll says Cingular charges $2.49 a minute from anywhere at sea to a U.S. city. Data transmission, such as text messaging, usually is 50 cents a minute. Using a stateroom phone for a ship-to-shore satellite call is $5 to $25 per minute, the CLIA reports.

Most major cellular carriers - Cingular, T-Mobile U.S., Sprint Wireless and Nextel - are linked with at-sea service companies.Verizon is linked with SeaMobile but not WMS.

Although some cruise lines, such as Royal Caribbean and Carnival, have no rules about where passengers may use cellphones onboard, others have set or are considering some guidelines.

At Regent Seven Seas Cruises, "We do request that guests set their ringers to vibrate, avoid loud conversations and do not use their cellphones in any of the ships' restaurants, bars or lounges," says spokesman Andrew Poulton.

Silversea Cruises asks guests not to use their cellphones in public areas, such as the restaurant, spa, shops, library, Internet center, show lounge, bar, casino and outdoor grill, says Brad Ball, director of corporate communications. "We understand that there is a need for some guests to be fully connected at all times, but they must respect the rights of fellow passengers," he says.

Norwegian Cruise Line asks people to avoid using cellphones in theaters and restaurants, and Holland America Line restricts use in all entertainment venues.