A Web surfer can click a phone icon adjacent to an ad, enter his or her own phone number and then click a "connect for free" button. Google's service calls the advertisers's phone number and when the Web surfer picks up the receiver on his phone, he or she hears ringing as the call to the advertiser is connected, according to a Google Click-to-Call frequently-asked-questions page.

Unlike Voice over Internet Protocol, a technology that sends voice transmission over the Internet, this service appears to connect two parties over the regular phone lines. However, Google declined to provide more details, including the specifics of the technology employed.

"We won't share your telephone number with anyone, including the advertiser," the FAQ stated. "When you're connected with the advertiser, your number is blocked so the advertiser can't see it. In addition, we'll delete the number from our servers after a short period of time."

Google said it pays for the calls, whether local or long distance. However, the Web surfer may incur airtime fees depending on the mobile phone plan used, the FAQ said.

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