Sometimes Google will not verify tracking numbers from third party providers, when trying to place them as a call extension.
This happens because their bots don't see the specific tracking phone number listed when crawling your site.
To bypass this, you will need to link your Google Ads account with Search Console.
To do this follow the steps listed below:
1. Log in to your Google Ads account and click on "tools"
2. From the Setup Menu, click on "Linked accounts"
3. Find "Search Console" and click on "Details"
4. Google will ask you if you want to link search console to Google Ads. Click on "Link"
5. Enter the URL of the site you wish to link and click on "Continue"
6. If the process is successful, you'll see "Linked" in the "Status" column. If for any reason you see any other status or the message that the account can't be linked to search console, consult the relevant Google Ads Help section here