Yahoo will open its mobile search to third-party content providers and let users search just by saying a term or asking a question.

The OneSearch 2.0 tool announced Tuesday will also show up on the home screens of some handsets, said Marco Boerries, executive vice president and head of Yahoo's Connected Life Division, in a keynote address at CTIA Wireless on Wednesday.

OneSearch 2.0 will bring up direct links to results from sites such as Yelp and Facebook that will take users to those companies' sites. For example, searching for a person's name will be able to automatically bring up results from major social-networking sites giving the number of members with that name on each system. A click on that result will send the user directly into a results page on that social network's mobile site. Similarly, a search for a restaurant will be able to bring up links to customer-review sites such as Yelp and Zagat. Which third parties come up will depend on relevance, Boerries said at a news conference following the keynote.

Last year, partners could arrange for these kinds of results by setting up business relationships with Yahoo. Now there is an open API (application programming interface) for it, the same one used for Yahoo's online search.

Yahoo has been aggressively pushing its presence on mobile phones, which could prove a potent market for advertising and content alongside the PC-based Internet. Despite Google's lead in online search, Yahoo has a richer set of tools on its mobile browser site and offers a downloadable application for phones.

Opening up OneSearch is just the latest attempt by Yahoo to make strides in the mobile Internet through openness. In January, Yahoo introduced new versions of both its mobile portal application and its site for mobile browsers. At the same time, it released documentation for developers to create "widgets" that can be added to both of them. Developers are allowed to include display ads and sponsored search, even from advertising networks that compete with Yahoo's.

"Opening up to other people's content ... can really drive extreme customer value that is good for both of us," Boerries said. The open search results are expected to start appearing in the second quarter.

With the voice-based search, users will be able to press a key and then say a term or ask a question and have search results appear on the phone's screen. In a demonstration at the keynote, answers to the question "What's the best place to play craps in Las Vegas?" came from the Yahoo Answers Web site. The system won't give any audio responses, Boerries said, but it should help mobile search reach even low-end phones, because the queries are processed on a server rather than on the phone.

Voice search in English will be rolled out in July and August. BlackBerry users can get a preview of the voice search function today at http://m.yahoo.com/voice, and previews will be available later for other platforms, Boerries said.

OneSearch 2.0 will also become easier to reach as it's placed on phone idle screens so users don't even have to open their browsers, Yahoo hopes. The company is writing downloadable applications for Nokia Series 60 and Windows Mobile that will let users place it there themselves, and it is working with Nokia, Motorola, LG Electronics and Samsung to get OneSearch integrated into the idle screens of phones they make. It will also approach carriers about this type of integration. Idle screen capability is expected to start rolling out in the second quarter.