This is the final post in our series on Google AdWords Ad Extensions . Previously we’ve covered:
- Google AdWords Location Extensions 
- Google AdWords Product Extensions 
- Google AdWords Sitelinks Extensions 
And today we’ll be rounding out the series by covering how to use Google AdWords  call extensions.
What Are Call Extensions & Why Are They Important?
Google’s help section describes Call Extensions as follows:
Call extensions make it easy for customers to call you directly from your ad and for you to better understand the value of your campaigns by measuring the phone calls that your ads generate.
Call extensions are a type of ad extension, an ad feature that allows advertisers to include additional information about their businesses and offering to their text ads. In the case of call extensions, this additional information is your business phone number.
Not unlike the other ad extensions we’ve covered, call extensions afford you additional real estate within a search result, and allow searchers a new means of connecting with your business right on the search result. This is key because it can increase both your click-through rate  and the rate at which you’re able to turn searchers into customers.
How Do I Set Up Call Extensions?
Like the other extensions, call extensions are very easy to set up:
Once you navigate to the ad extensions tab, select “Call Extensions” from the view drop-down, and click “New extension.” Then you simply have to fill in your information:
The one wrinkle here is the unchecked boxes above, call-only format and call metrics:
- Call-only Format – This means that your phone number – and only your phone number – will be clickable from mobile devices, and searchers on smart phones will be able to initiate a call directly from your ad.
- Call Metrics - This is a tracking mechanism you can enable through Google in which Google will assign and display a custom phone number for your ad for tracking purposes (calls will be rerouted to your number) so that calls will show in your AdWords reporting interface.
Note that the tracking functionality for call metrics will cost you $1.00 for every click. This may well be worth it for you, but you might also consider alternative call tracking solutions like Mongoose Metrics  (better call tracking can be a great help in demonstrating the value of your PPC program ).
When to Use Google Call Extensions
Call extensions can be a handy tool for any campaign, but are particularly valuable for local campaigns and campaigns where mobile impressions are likely. Important to note is that if you’re doing a significant amount of call volume you should work to have some PPC tracking for this action in place – either via call metrics or, as we mentioned above, via another vendor.