Verizon Wireless, the nation's No. 2 cellphone company, is upping the ante in the highly competitive telecom industry by targeting high-volume users.

The communications giant is expected to announce today a calling plan that offers customers unlimited minutes anywhere in the United States for roughly $100 a month.

That means even the most talkative customer — ranging from the compulsively chatty who routinely run over their minutes to business professionals who never stop working — will be able to converse worry-free at any time, company officials said.

"It's a first in the industry," said Mike Lanman, chief marketing officer for New York-based Verizon, adding that he thinks the plan will appeal to about 15 percent of cellphone users, or more than 30 million.

"We made this tremendous investment because our customers said they want predictability in their phone bill," he said.

The move is the latest salvo in the telephone wars that have seen all the major companies offer more and more plans to try to gain market share.

An analyst briefed by Verizon Wireless described the company's $99.99 anytime-minutes plan as bold. He said it is likely to put pressure on competitors, including the No. 1 carrier, Atlanta-based AT&T Mobility, to play catch-up.

"This is a very aggressive move for the high-end user," said Roger Entner, senior vice president for the communications sector for IAG Research. "It is basically forcing everyone else to follow. I would expect comparable plans in six months."

Verizon Wireless said last month that it had 65.7 million subscribers. AT&T Mobility had 70.1 million subscribers at the end of 2007.

AT&T officials could not be reached Monday to see if the company plans to offer a competing product.

Verizon Wireless also will announce today a lower-priced broadband plan — about $40 a month — for consumers who wirelessly connect to the Web with their laptops.

The calling plan starts immediately, and the broadband plan will be available March 2.

Unlimited service is not a new idea. Metro PCS and smaller carriers offer plans that are specific to cities or to larger regions.

But Verizon's deal is significant because it's the first time a company is offering the deal nationwide without it being a sign of financial desperation, Entner said. It also pre-empts Sprint, which Entner said has been looking at a similar plan.

The challenge for Verizon Wireless will be making sure overusers don't harm the company's network.

"They will certainly watch for potential abusers, like people who use their cellphones as baby watchers," he said. "They will monitor those who use, say, 10,000 minutes a month."

Cellphone companies are trying all sorts of product and plan promotions to attract new customers.

For instance, AT&T in September launched a program dubbed "Smart Limits" that lets parents dictate when their children could receive calls, block downloading functions and restrict the number of text messages.

Verizon Wireless over the holidays added more beef to its hardware lineup, offering new phones, including the Voyager, a combination of mobile TV, touch-screen technology and removable memory in one sleek unit.

In previewing its announcement, Verizon Wireless did not shy away from hyperbole, calling the plan "game-changing." But Lanman said he think the hype fits.

"We think it is going to change customer usage patterns," he said.