Just like your Ad needs to be approved by Google so does the Phone Number you would like to use in the Ad.
If you've gotten a message from Google, showing as 'disapproved can't verify', then it sounds like AdWords call extensions has invalidated your phone number as they were not able to verify that the number is legitimately associated with the business.
There are 3 ways to verify that you own a phone number
- The number must be hard coded on the website. You can accomplish this by adding the following code to the website (replacing 0123456789 with your call tracking number - omitting spaces and dashes) (in the <body> tag):<div style="display:none;">01234567890</div>
- Prove you own the domain by linking your adwords and search console accounts together.
- Prove you own the domain by putting the adwords conversion tracking code or remarketing tag on the website.
You can learn more here: