But skeptics note that there's a good reason that half of local businesses don't have Web sites: They do perfectly fine without them. And while it's a bit much to expect the local liquor store or drycleaner to setup an Adwords account, mom-and-pop businesses are more likely to go for an established form of advertising that gets their message across to local customers cheaply.

Local radio gives small businesses that opportunity while giving Google another avenue to bring these businesses under its fold. Using the medium, the company has a huge opportunity to make money from even those small businesses that don't want to go through the hassle -- or see the benefit -- of setting up a Web site.

"While half of these businesses don't have Web sites, I'd bet that almost all have telephones," says Matt Booth, an analyst at Kelsey Group. And Google is currently testing technology that will allow businesses to trace the advertising origin of each customer call, which CEO Eric Schmidt lists as a key priority, Booth says.

Pay-per-call technology places different phone numbers into different ads and routs all customer calls through an existing phone system while keeping track of which number was dialed. This lets companies know which ad spurred a customer's call -- and how to value each advertising mode -- without any significant changes in their own communications systems.

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