With every update, WhatsApp adds something new to its existing set of features. This time, it's the voice call feature that's being upgraded. Since calling has become a basic function of the messaging service, WhatsApp is testing the ability to set certain contacts as favorites. This allows you to reach with a single tap instead of fiddling around in the contact list.

According to the latest report from WABetaInfo, WhatsApp beta #24.3.10.70 for iOS reveals that the app will soon let you set contacts as your favorites.

As shown in the screenshot below, you can search for contacts and add them to your favorite list. These contacts will (likely) appear at the top of the Conversations tab. So you can tap their name to call them without much delay.

I assume this feature will work similar to how you can pin certain chats. Pinned contacts always appear at the top of the chat tab. Currently, the calls tab only shows a log of the calls you've made and received in the app. To make a call, you must first scroll through the log to find the number and then call the person. Or you can go to their profile and call them. "Favorites" contact will simply this experience.