The Mountain View, Calif.-based company is now inviting U.S. consumers to call 1-800-GOOG-411 from any phone to test Google Voice Local Search located on its Google Labs site.

"Using this service, you get fast access to the same local information you'd find on Google Maps," the Google Labs site explains. "You don't need a computer, you don't need an Internet connection, and you don't even need to use your cell phone keypad."

Google's 411 experiment comes on the heels of rival Microsoft's plan to buy Tellme, a directory assistance provider and voice-activated mobile search firm, reportedly for between $800 million and $1 billion.

These overtures were predicted late last year by Matt Booth, program director for interactive local media at market research firm The Kelsey Group.

That portals including Google, Yahoo, and MSN would become major players in mobile voice search--and use mobile directory services to launch new "opt-in" marketing businesses--was all but inevitable, according to a report released by Kelsey.

There are a variety of factors pushing the portals into directory assistance, according to Booth--including the proliferation of mobile devices and the falling cost of handling voice information requests. Google, for starters, generates about 10 cents of revenue for every online search it gets.

"If you can service that call for less than 10 cents, then it makes sense for a whole lot of people to look at this market and start getting into it," said Booth.

Google Voice Local Search can be used from both mobile phones and land lines. Mobile callers can request listing details to be sent as a text message to their phones. The service is operated automatically entirely by computer. Google said it is seeking to fine-tune the service--operated automatically entirely by computer--to better recognize user requests.

The Kelsey Group estimated that directory assistance generated 6.3 billion requests last year through land line, wireless, and VoIP communication. Traditional directory assistance providers that charge $1.50 on average per call were expected to generate $9.4 billion in 2006.

In addition, Kelsey analysts estimate the U.S. directory assistance market generates $9.4 billion a year. Worldwide, the market amounts to some $13 billion, according to data published by Opus Research.

Competing with the portals are a growing number of companies such as 1-800-FREE411, which provide free directory assistance by requiring consumers to listen to an ad before receiving assistance.

Dating back to 2002, Google has experimented with voice-based search services that return text-based results to mobile users.

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