Expect to see a steady decline in the growth of mobile subscribers in the United States.

Analysys Research predicts that total annual subscriber growth nationwide could fall to 2 percent a year by 2012, compared with the 11 percent to 14 percent growth posted by the three wireless carriers, AT&T, Verizon Wireless and T-Mobile USA. But add in Sprint Nextel, which posted two consecutive quarters of subscriber losses, and the total annual subscriber growth last year for the top four carriers dropped to 9 percent -- the slowest growth in a decade.

"What is causing the slowdown? The market has matured and to put it simply, we're running out of new subscribers," said Jason Kowal, U.S. head at Analysys, Washington. "We think the U.S. can learn how to respond to saturation by looking at Europe where this happened five years ago."

Mr. Kowal will make this point to customers and prospects at this week's GSMA Mobile World Congress organized in Barcelona by the GSM Association.

Analysys estimates an 85 penetration of mobile subscribers as part of the U.S. population last year. By contrast, Britain reached that milestone as far back as 2002. At that penetration level, both countries registered a 9 percent annual subscriber growth, but Britain dropped to 4 percent in 2006.

The total number of U.S. mobile subscribers at the end of last year is estimated at 258 million. By 2012, the mobile population will grow to 318 million.

"Still a lot more, but if you draw a line between the two, it's not as steep as it should be," Mr. Kowal said.

The average revenue per user has been more or less flat, he said, so if it boils down to a volume game then the only way out is more subscriber growth.

Subscription prescription
What should U.S. carriers do in the face of this eventual subscriber slowdown? Analysys offers several fixes.

First, maximize revenue from prepaid customers, a segment that generates considerably more income in Europe than it does in the U.S.

Second, differentiate between contract and prepaid offerings. Create a separate brand for prepaid simply to stem the migration of contract customers who generate a high average revenue per user.

Third, use data mining for targeted retention efforts to retain the loyalty of existing customers. Fourth, examine the possibility of new revenue from femtocells, or small cellular base stations for use in residential areas or small businesses.

Fifth, make non-voice services such as mobile media and entertainment more attractive with clear content prices to customers. Finally, move out of areas that don't fall within a carrier's core competency and hand those tasks to specialists.

"The most important message to get across is to find more ways to connect the operator to the customer to get them to spend more money," Mr. Kowal said.

"This has to do with the operating system and basically making that easier to navigate," he said. "This has to do with how they customize the presentation. So this is definitely a mobile marketing issue, but there's a data-mining component to it.

"The operators should do anything they can to make the mobile device the center of the customer's universe for more personalization, for more ways to take pride in your handset."