'Call back' button is a new feature of WhatsApp. How does it work?

The Meta-owned service has added a feature that will make it simpler and faster to contact back the person who originally placed the call in order to make missed WhatsApp calls more noticeable.

WhatsApp introduces "Channels," a one-way tool for updating users.
According to WABetaInfo, a website that analyses news and updates pertaining to WhatsApp and was the first to publish about this option, this function is known as "Call back."

What does "Call back" entail?
According to a screenshot posted by WABetaInfo on its website, WhatsApp's event notification that appears when a call is missed now includes a callback option.

The WhatsApp "Call back" function

Also, as can be seen in the image above, one only needs to hit the button in order to call the original caller back (thus the feature name).

Why is WhatsApp introducing this function?
WhatsApp "wants to make it apparent that the messaging event is dedicated to the prospect of contacting back the contact after receiving a missed call," the article claims.

Availability
In order to test it for any potential bugs or shortcomings before a more widespread rollout, the instant messaging service has for the time being restricted access to the "Call back" feature to a small group of beta users. You shouldn't be concerned if you can't find this update on the Microsoft Store; it will be made available to more people over the next few days.