Build your Campaign same as you would any other Search Campaign.
Except – Under Ads Set-Up click on the Call Only tab.
Create your Call Ads.
Click Preview to review.
If all looks good, Save your Campaign.
When ready to export over to AdWords Editor – click Build.
Copy and paste your files into AdWords Editor.
When copy and pasting your Call Only ads make sure that you paste them under Ads>Call Only Ads.