Updated

Google Inc. is joining EarthLink Inc. in a bid to build a wireless network in San Francisco that would offer basic Internet access for free and charge about $20 per month to surf the Web at higher speeds.

The partnership, revealed late Tuesday night, represents the first time that Google has acknowledged it wants help in its quest to provide free wireless, or Wi-Fi, service throughout San Francisco, where the hills could make reliable Internet connections more difficult.

Google, which runs the Internet's leading search engine, and EarthLink, a major Internet service provider, had been bidding against each other but recently decided it made more sense to team up.

Under the partnership, EarthLink would pay for most of the projected $15 million cost to build and maintain San Francisco's Wi-Fi network over 10 years, said Don Berryman, EarthLink's president of municipal networks.

EarthLink would recover some of its expenses by charging about $20 per month for Internet access about 20 times faster than dial-up service, Berryman said during a Wednesday interview. Google's free Wi-Fi alternative would be about five to six times quicker than dial-up.

EarthLink has won a similar 10-year contract to provide Wi-Fi coverage to Philadelphia. There, EarthLink will sell the service wholesale to Internet service providers for $9 per user per month.

In San Francisco, the joint bid by Google and EarthLink is competing against five other proposals. The other finalists are: Communication Bridge Global; NextWLAN; Razortooth Communications LLP; MetroFi and SF Metro Connect, a partnership that includes SeaKay, Cisco Systems Inc. and IBM Corp.

San Francisco hopes to pick a winning bid in April, paving the way for its Wi-Fi network to be switched on late this year.

Several other large cities, including Chicago and Minneapolis, are working with the private sector to build Wi-Fi networks, but the San Francisco project has been among the most closely watched because of Google's interest in blanketing the 46.5-mile-square city with free Internet access.

If San Francisco picks the proposal from Google and EarthLink, it would become the largest U.S. city yet to offer a free Wi-Fi service.

The San Francisco bid has spurred speculation that Google some day hopes to build a national Wi-Fi network to ensure more people have Internet access so they can view the moneymaking ads distributed by the company's search engine. Online advertising accounted for the bulk of Google's $1.5 billion profit last year.

Under Google's San Francisco proposal, the free Wi-Fi access will be financed by ads.

Google so far has stressed that it's only interested in building large Wi-Fi networks in San Francisco and about 35 miles to the south in Mountain View, where the company's headquarters is located. Google hopes to launch the Mountain View network in June.

Google didn't explain its reasons for joining EarthLink in a Wednesday statement.

This isn't the first time that Google and EarthLink have worked together. Google has been running the search engine on EarthLink's Web site since 2002.