In order to do Click to call, go to people profile page, by clicking on the name of the contact in the contact listing page, as show below. Like below , if you want to call Manish, click on the name of Manish.
When you click on the name of Manish, the people profile page would open. When that opens Click on the phone icon as shown on the below image.
When you do that the call widget would open. When the call widget opens, click on the call button, and the call will go as shown below.