joined:Sept 7, 2002
Clicking the ad which has a phone icon to the right of the 1st line of text (very "clickable" / "noticeable") brings a drop down where you can enter your phone number and click on Connect for Free - as well as a check box to save my number to computer. Once the PPC ad is clicked, it also gives a longer PPC description.
Now, how do advertisers sign-up.
Here is Google's help page on the subject, [google.com...]