Using ad extensions in Google AdWords place phone numbers in the body of your ad copy, allowing you to display a phone number in search results before the visitor navigates to your website.
For best results, we recommend that you do not use the same tracking number in your ad extensions that you use on your website for AdWords visitors. A dedicated tracking number for your ad extensions will make it much easier to identify the true source for those callers.
If you are tracking both AdWords (visitors who click an ad and come to your website) and ad extension calls, we recommend this setup:
Use a tracking number associated to the source “Google AdWords,” which will be displayed dynamically to visitors when they click through to your website from one of your AdWords ads.
Use a tracking number associated to an off-site source such as “Ad Extension,” which you can display in your ad extension. Set up our integration with Google AdWords to receive campaign data from Google for the ad extension calls in your call log.