Are you trying to track the number of clicks on the link or are you trying to implement a call tracking solution that provides extra services such as call recording etc.
If trying to track the number of clicks then the process is as follows
1.Fire an event using Google Tag Manager (GTM)
2.Track event with a Google Analytics (GA) goal.
1)To fire the event in GTM create a new Universal Analytics Tag with a track type of "Event" fill in the Category, Action & Value (if you want to nominate a value to the event). The Category, Action can be anything you want but you will need this detail later. For Label click the little lego button to the right and select the "page url" or "page path" variable.
You then want to add a trigger of type "Click" on "just links". In the section that says "This trigger fires on" select "Some Link Clicks"
In the drop-down select "Click URL" then "contains" and then in the text box enter "tel:" without the double quotes.
Save and publish you GTM container
2) Go to GA->Admin->View->Goals and select "New Goal", choose custom from the menu. Then Name your goal and select "event" as the Type.
In the Goal Details section enter the category & action name you used in GTM(this has to be exactly the same) Leave the Label & Value fields blank.
This goal will now appear in Conversions->Goals in your GA reports