SAN JOSE, Calif. - Attention iPhone owners: AT&T has heard your complaints about its sometimes-slow network.

A word of warning, though: You may not like what the company has in mind.

AT&T is mulling a new pricing plan that would force its biggest data users to pay more than others. That would be a sharp change from the company's current plan, where it charges users of Apple's iPhone and other smart phones a flat monthly rate for unlimited data usage.

The proposal, which isn't final, is a possible response to traffic patterns on AT&T's network, Ralph de la Vega, president and CEO of the company's mobility and consumer division, said at an investor conference in New York on Wednesday. Just 3 percent of smart phone customers account for about 40 percent of the traffic on the company's wireless data network, he said.

"We're going to try to focus on making sure we give incentives to those small percentages to either reduce or modify their usage so they don't crowd out the other customers in those same cell sites," de la Vega said.

Soon, the company plans to send real-time updates to customers who are using excessive amounts of data, he said. But, he added, "longer term, there's got to be some sort of a pricing scheme that addresses the usage."

De la Vega did not say when AT&T might roll out such a pricing scheme, how much it would cost consumers or how much data consumers would have to use before they'd be affected.

No matter, many iPhone users took to Internet message boards and social networks to bash AT&T for even considering the idea.

Among them was Patrick Leal, 38, who bought the original iPhone two years ago and now owns an iPhone 3G. A technical writer from Los Gatos, Calif., Leal said he uses his iPhone every day to read news, check stocks and connect to Pandora's Internet radio service. While he's run into dead spots where his phone calls drop, Leal said he hasn't had any problems with his iPhone's data connection.

Leal said he understands the position AT&T's in, but still would be "pretty mad" if he had to start monitoring his data usage because the company no longer offered an "unlimited" plan.

"They're admitting that their network is slow," he said. "They're admitting that they can't handle the capacity."

San Francisco resident Earl Neconie, 52, said he was "shocked" at AT&T's plans. Neconie, who is a graduate student at San Francisco State University, has had an iPhone since the first one was released and now owns the latest model, an iPhone 3GS. If AT&T ends up putting in place the pricing plan, Neconie said he would consider unlocking his iPhone and switching to T-Mobile.

"Unlimited data was the reason I chose the iPhone and AT&T," he said.

The iPhone has been something of a mixed blessing for AT&T. The device has attracted millions of new users to the company's wireless service. But the reputation of that service has taken a battering thanks to the loudly voiced complaints of iPhone users. And the company's network has clearly been taxed by iPhone customers, who account for the lion's share of Internet data usage today.

De la Vega defended the company's record, but he acknowledged a few problems. Service provided to wireless customers in San Francisco and Manhattan is "below our standards," he said.

But he said it's working to beef up its service in both cities. "In both of those markets, I am very confident that you are going to see significant progress, and our company is committed to bringing those two markets up to the standards that we are seeing in the rest of the nation," he said.

An Apple representative declined to comment on de la Vega's announcements, deferring instead to AT&T.

(c) 2009, San Jose Mercury News (San Jose, Calif.).

Distributed by McClatchy-Tribune Information Services.