As more mobile phones come equipped with Internet access, big companies are still figuring out how to provide wireless users convenient access to one of the most basic Web services: search.

Yesterday, Dulles-based America Online Inc. said it was testing a new technology from Israeli software maker InfoGin Ltd. that converts Internet pages into a format that's easier to read on small cell phone screens. It allows users to search the Web, shop for products and get local movie listings.

Current search functions are geared toward computers with full-size screens and are hard to use on small mobile devices, which often freeze the browser or require an inconvenient number of clicks.

"It's a really frustrating experience," said Himesh Bhise, vice president for AOL Mobile.

"Everybody's experimenting" with simplified mobile search tools, said Julie Ask, a research director at Jupiter Research, a market research firm. "It's still early. It's still free. It's not profitable," and there are not a lot of sponsorships yet, she said. "It's not clear who's leading the pack, because there's not lots of revenue. But there will be."

Google Inc. and Yahoo Inc. offer a service that allows users to search by sending a text message to a five-digit phone number. The search tool then generates an answer and sends back weather, sports scores or restaurant information. In addition, Yahoo allows a scaled-down version of Web searching that pulls up links to relevant images or Web sites. AOL and Google offer search functions that generate maps or driving directions. Software providers such as Vindigo Inc. also sell online city guides for cell phones.

As the mobile Internet experience improves, companies hope searching will generate advertising dollars -- eating into services such as 411 information calls that generate $6 billion a year in the United States, according to the Pierz Group, a firm that tracks the directory business.

Most of the roughly 190 million cell phone users in the United States have the ability to send messages or get Internet access through their phones -- a huge base that businesses could target by pairing ads with a shopping or movie search. Mobile users are likely to search for localized information -- movie listings, store and restaurant locations, traffic reports -- and that may be of special interest to local advertisers, analysts say.

"Today we do not charge for our search function, [but] I think there's certainly potential in the mobile space" for ads and some revenue-sharing with wireless carriers, said Mihir Shah, director of product management of Yahoo Search.

Yahoo is trying to make searching easier by using shortcuts that display the likeliest answer to a query at the top of the cell phone screen, he said, so that if a user types in a W and the Zip code, the day's temperature appears on the screen.

Still, online searching is hard to format for the cell phone, said Greg Sterling, an analyst with the Kelsey Group, a market research firm. Different wireless devices run on different types of software, which makes it hard to deliver a uniform format. Search providers also must work out arrangements with the carriers, which are the gatekeepers of content on the network, he said. "It's a much more complicated proposition."

Companies are trying to find an easy way to let cell phones search the Web to, say, find a movie.