Google Inc. is testing a click-to-call service that lets users speak over the phone to an advertiser found on the search engine's results page.

Advertisers participating in the program have a phone icon next to their text advertising, according to a frequently asked questions posting on Google. Clicking on the icon displays a field to enter a phone number that can be sent to Google, which will call the number provided and connect the person to the advertiser. The calls are free to consumers.

The telephone numbers are not shared with advertisers or anyone else, and are kept on Google servers for no longer than four months after the last time a person uses the service, the Mountain View, Calif., company said. Numbers are deleted permanently after that time.

The advertiser's number, however, will appear on a person's caller ID when Google makes the connection, giving the consumer the option of saving the merchant's phone number.

Google did not say whether a third party was involved in making the call.

"Google is always considering new ways to provide value to its advertisers and we frequently run tests of potential new features and products," the company said in a statement confirming the test. "We are currently conducting a limited test of a pay-per-call model, but we don't have any additional information to share at this time."

Click-to-call features are particularly helpful to advertisers who provide services, such as financial institutions or law firms, experts say. Google is not the first to offer such a service, which is available on rivals Yahoo Inc. and America Online Inc. The latter provides the service through partner Ingenio Inc.

Online marketplace EBay Inc. is expected to eventually make a click-to-call service available through its recent acquisition of Internet telephony company Skype Technologies SA.