Found on Google Inside that Google are to launch a Click to Call service on Adwords.

On Search Engine Round Table they show what happens when a user clicks that ad.

I can see this possibly (and I stress, possibly) having a few major effects:

• People clicking it just to see what the icon means, but not interested in the sponsor (although the sponsor probably won’t get charged unless a valid number is entered)
• People doing the above, but enter false numbers
• People playing pranks on their friends (by entering their number, so they get calls from random companies)
• Or maybe people actually do want a call back.