We have been experimenting with Call Only Campaigns in Google AdWords.
Call Only Campaigns are like regular search campaigns but they are only eligible to run on mobile phones. Basically, a user sees your ad, clicks on it and their phone app opens with your number pre-dialled.
And it doesn't matter where a user clicks. There is a Call Now button on the ads, but wherever they click, the result is the same - they are primed to place the call.
At this point we find many people panic. They simply weren't ready to place a call to your business. They were expecting to be redirected to your website and then have the opportunity to browse your offer, find out a little more about your company and then... maybe... give you a call.
Instead, most people simply drop their phone and wonder how they did that.... "Surely I didn't hit the Call Now button, or did I ??"