When setting up a Google Search Ad, you have the option to create what is called a "Call Only Ad".
These ads look like this in the Google search results:
The ads are only shown on mobile devices, so if you're trying to reach a business audience who uses their desktop computer a lot, it already puts you at a disadvantage.
When the user clicks on these ads, it will open up their phone app and prompt them to make the call. They have to press the call button to actually make the call still after clicking the ad. Meanwhile, you the advertiser were still charged for the ad click even if they don't follow through and make the call.
This happens quite a bit because these type of ads are rare and so a lot of users who click expect to go to a website first, you know, like how every other search result works on Google.com.
As you can tell, I'm not a huge fan of Call Only Ads. Is there ever a case where you should use a Call Only Ad though?
I can only think of one; the client has a website that you can't set up Google Ad Conversion Tracking on and they can't afford or are unwilling to have a new website created.
I've come across a situation like this once with a massage spa and Call Only Ads were the only practical option because at least we could track call conversions. Running a Google Ad Campaign with no conversion tracking is not an option IMO.
If however, you have a website you can set up conversion tracking on, it's better to run normal search ads. You can still add a call extension if you want the user to be able to call directly from the ad. It's a better user experience than Call Only Ads and is apparent to the user that they're about to make a phone call.