In order to verify the phone number used in your ads Google will crawl your website to confirm the phone number is matched. However, as the tracking phone number used in your ads may be different to the one on your website you may find that your ads are disapproved when the tracking number cannot be matched.
If your ads have been disapproved, Google offers the solution in the following support article:
Expand the Troubleshooter: Unverified phone number section for the following instructions and links:
Delacon highly recommends the Verify domain ownership option as this provides an ongoing approval for any tracking numbers in use and avoids future ad disapproval.