Click 2 call
With Click to Call campaigns, you pay for clicks.
When the searcher clicks on the ad, there is an extra step on their phone to actually make the call. Not everyone makes the call.
I've seen as good as 70% and as bad as 10%. Comes down to whether people are actually expecting to make a call. If it is for an emergency plumber, they probably are... Other industries, not so much.
So even though the ads clearly indicate phone calls, in reality it doesn't work out perfectly.