In a move that could shake up the mobile-phone industry, AT&T said Wednesday that it will become the first major carrier to stop offering new customers “all you can eat” data plans and shift to charging them based on their usage.

The new pricing, which AT&T will put in place next week, will be optional for existing customers, and comes as Apple is widely expected to introduce its latest iPhone Monday. AT&T is the exclusive carrier in the United States for the popular phone, which has created bottlenecks on its network, particularly in cities including San Francisco and New York, where users consume large amounts of data.

Other carriers could mimic AT&T’s move, analysts said, setting a trend that could reshape how customers pay for data on mobile devices such as smartphones and tablets like the iPad. Broadband providers in general — wireless and wired — have talked for years about moving away from unlimited data plans and have conducted limited experiments with tiered pricing.

AT&T’s move comes as consumers increasingly use their phones to check e-mail, watch videos, locate shops and surf the Web as well as to make calls. Those activities frequently require more bandwidth than phone calls.

“Clearly this is a pain point for all operators,” said Charles Golvin, an analyst with Forrester Research, an industry research firm. “They need to address the challenge that unlimited plans can promote usage that can become a problem for the network.”

Andrew Jay Schwartzman, senior vice president at the Media Access Project, a nonprofit public interest law firm that focuses on broadband issues, said other carriers are likely to follow AT&T’s lead.

“My guess is (AT&T’s competitors) will watch for a while and then try some variant on the same thing,” he said.

AT&T portrayed the move as consumer-friendly. Under the new pricing system, customers can pay $15 a month for an entry-level plan with a cap of 200 megabytes a month. A $25-a-month plan will allow them to transfer up to 2 gigabytes of data in a month.

Currently, the company charges smartphone customers $30 a month for unlimited data usage. That rate is a barrier for consumers who don’t have a smartphone but are interested in getting one, said AT&T spokesman John Britton.

“We’re trying to make mobile data more affordable for more people,” he said.

Britton asserted that the new plans will benefit the bulk of AT&T’s existing smartphone subscribers. According to AT&T, 65 percent of its smartphone customers use less than 200 megabytes of data a month and 98 percent use less than 2 gigabytes of data each month. A gigabyte is enough for hundreds of e-mails and Web pages, but it’s quickly eaten up by Internet video and video conferencing.

However, the move comes amid well-publicized problems for AT&T in handling the data traffic generated by iPhone users. Previous reports have shown that a disproportionate portion of the Web surfing done on mobile devices is done on iPhones. And the 200,000 available applications have encouraged iPhone users to use their phones in novel and sometimes data-intensive ways, from streaming music from their home computers to streaming online videos to getting turn-by-turn directions.

Consumers who exceed the caps — even by only small amounts — will see sizable charges. Britton noted, though, that consumers on the lower-end data plan can switch mid-month to the higher-end plan if they see they are going to go over their limit and can switch back the following month. AT&T is providing consumers a number of tools to monitor data usage and will text message customers when they reach certain levels.

Analysts said AT&T’s move was to be expected, given the increasing amounts of bandwidth iPhone users have been consuming — especially with a new, multitasking iPhone operating system expected to be released this month. That feature alone could bump many iPhone users into a higher, more expensive pricing tier.

The new iPhone operating system could increase data consumption by 25 to 30 percent because it will allow customers to run multiple Internet-connected programs simultaneously, said Chetan Sharma, an independent wireless analyst.

“It was inevitable; unlimited data pricing was completely unsustainable,” he said.

Consumers expressed mixed emotions about the move. Some worried that they might be negatively impacted by the caps.

James London, a 20-year-old De Anza College student, uses his iPhone for a lot of data-intensive tasks, including streaming video.

“I’m not the happiest person about it,” London said. “But it could be worse.”

Others figured they’d be unaffected by the data caps. Albert Poon, a 41-year-old San Francisco resident, said he uses his iPhone all the time, but has consumed only 1 gigabyte of data in the past two months.

“I can’t imagine two gigs is going to cramp my style very much,” he said.

Verizon Wireless, the largest wireless carrier and AT&T’s chief rival, had no immediate comment on AT&T’s move. There has been much speculation that Verizon may sell its own version of the iPhone.

For the iPad, the tablet computer Apple released a few months ago, the $25-a-month 2-gigabyte plan will replace the $30 unlimited plan. iPad owners can keep the unlimited plan as long as they keep paying $30 a month, AT&T said.

The Associated Press contributed to this report. Contact John Boudreau at jboudreau.mercurynews.com. Contact Troy Wolverton at twolverton@mercurynews.com. Follow him at Twitter.com/troywolv.