OVERLAND PARK, Kan. — Nathan Bales represents a troubling trend for cellular phone carriers.

The countertop installer traded in a number of feature-laden phones for a stripped-down model. He said he didn't like using them to surf the Internet, rarely took pictures and couldn't stand scrolling through menus to get the functions to work.

"I want a phone that is tough and easy to use," said Bales, 30. "I don't want to listen to music with it."

But the wireless industry needs him to be comfortable with advanced features and actively use them. As the universe of people who want a cell phone and don't already have one gets smaller, wireless carriers are counting on advanced services to generate the bulk of their future revenue.

Consumers paid $8.6 billion last year for so-called data applications, up 86 percent from the year before, according to wireless trade group CTIA.

But they've also shown a growing frustration with how confusing those added features can be. A J.D. Power & Associates survey last year found consumer satisfaction with their mobile devices has declined since 2003, with some of the largest drops linked to user interface for Internet and e-mail services.

That has providers working hard to make their devices easier to use — fewer steps, brighter and less-cluttered screens — so consumers will not only use data functions more often but also be encouraged to buy new ones.

At Sprint Nextel Corp.'s operations campus in suburban Kansas City, a trio of researchers recently watched through one-way glass and overhead cameras as a volunteer navigated her way through a prototype program that lets parents set limits on their children's phone use.

The observers monitored how many steps it took for the woman to make the program work, how easily she made mistakes and how quickly she could get herself out of trouble. The results could be used to further tweak the program, said Robert Moritz, director of device development.

"If you bring somebody in and they have problems, it's not because they're dumb, but we were dumb with the design," Moritz said.

Other major wireless providers also are trying to improve their devices and programs.

Verizon Wireless, for instance, is trying to push its designs so users can accomplish many things with one button press.

"It's not fun to download a ring tone and have to figure out how to get that on your phone," said Verizon spokeswoman Brenda Ramey. "We do not shy away from testing. If the device or service doesn't work, it's a reflection on our network."

T-Mobile also has tried to cut down the number of steps needed to perform a function such as taking and sending photos.

Ease of use can be a competitive edge. Industry experts say the companies understand that.

How well they're doing is a different matter.

Roger Entner of the market research company Ovum said most of the major carriers are trying to replicate how people use personal computers instead of coming up with a new approach.

"What do (customers) do best on the phone? They talk," Entner said. "What do they do worst? Type. Why is every user interface based on typing?"

Charles Golvin of Forrester Research said a recent survey indicated few cellular customers choose a phone based on its usability, typically because they either don't think there's anything better or, like Bales in Kansas City, don't think they need those services.

But Golvin said for the market to truly grow, the programs and phones are going to have to become appealing to users other than tech junkies.