Calls can be tracked via the Google Ads DNI snippet, Google Analytics, or a third party application.
Google DNI - one way to track calls going to a landing page is by creating and installing a Google DNI (dynamic number insertion) snippet. Googles DNI snippet will report on: call start and end time, location, area code, answered or unanswered, duration, and conversions.
Google Analytics - Some advertisers do not want their phone number to be altered. In that case, you can create a trigger for phone link clicks within Google Tag Manager. GTM will then collect and send that information to Google Analytics. From GA, you can create a goal for phone click events and then import the goal into Google Ads. To view report information (other than conversions which you can see in Google Ads) you'll have to log in to the Google Analytics interface.
Third Party - If you'd like to be able to not only see conversion data but also listen to call recordings, see who called (name, number, and location), and see historical interactions with that person, then you'll need a third party application. We recommend using CallRail, which easily integrates with Google Ads. However, there are other great alternatives such as Call Tracking Metrics that will get the job done as well.