SAN DIEGO (AP) _ An emerging generation of wireless phones, pagers and other communicators appears likely to get stuck in technical trouble.

Personal communications services, known as PCS, are often touted as working throughout the United States and even the world.

But manufacturers and network providers are choosing transmission methods that aren't always compatible, creating a patchwork quilt of signal.

``There's no way it's going to be seamless at first,'' said Laurence Milstein, acting director of the Center for Wireless Communications at the University of California at San Diego. ``In order for it to be, a given technology would have to permeate every area.''

Milstein could not estimate when he believed seamless operation would be possible. ``I wish I knew,'' he said.

The problem is the new devices use signals in which everything, including voices, has been converted into the digital language of computers. Doing so allows voice and data signals to intermingle, making greater use of scarce airwave space.

But seven different methods for the digital transmission process have been proposed, and carriers are free to choose.

The Federal Communications Commission decided not to impose a single standard on companies. The FCC auctioned two PCS licenses in each of 51 areas of the country known as ``major trading areas.'' In total, carriers paid $7.03 billion during the auction that ended in March.

``The industry is suited to determine which standards are best. The marketplace will determine everything works out in the best public interest,'' said FCC spokeswoman Stacey Reuben Mesa.

The problem is similar to one that confronted consumers in the 1980s, when videocassette recorders became popular with two different standards, Sony's Betamax and VHS.

After several years of dueling standards, the market settled on VHS, although Betamax was widely regarded as the better format.

With the new wireless devices, consumers may be forced to choose between technologies without knowing much about them, UCSD's Milstein said.

And there is no guarantee that all standards will survive, meaning some carriers _ and customers _ may have to change in midstream.

Several solutions to the PCS incompatibility problem have been proposed, including:

_ Dual-band devices that would work on both traditional cellular and the new PCS frequencies. The drawback is the consumer would be paying for two phones in one unit.

_ A network that can work with all the standards. Such a solution is being worked on by Steinbrecher Corp. of Burlington, Mass. but some people have feasibility questions.

_ Devices that include several transmission standards. The consumer, however, would be paying for a second or third standard.

``Any technology that gets built out the way we're talking is going to hit speed bumps along the way,'' said Jeanine Morley, an analyst with Brenner Securities in New York.

Recent announcements by leading developers of new wireless systems illustrate the trouble.

PCS PrimeCo, a Dallas-based consortium of Baby Bells and AirTouch Cellular, chose a transmission technology called CDMA, or code division multiple access. CDMA was developed by Qualcomm Inc. of San Diego.

But other companies, such as Pacific Bell Mobile Services, chose another standard known as GSM, or Global System for Mobile Communications. It is popular in 70 other countries.

AT&T and Sprint, the two largest winners in the PCS auctions, have yet to announce a digital standard.

CDMA is widely regarded to be the better technology in theory, but it has not been tested on a wide scale.

``To us, it's not a question of CDMA not being a good technology _ we just don't know,'' said Lou Saviano, spokesman for Pacific Bell's Cellular Services. ``We have a business to build here and want to build it pretty soon.''