One of the key features for WhatsApp is the ability to make and receive calls over Wi-FI without burning through precious call-time minutes on your cell phone plan. To make a call through WhatsApp, the person you're calling must also have the app installed and set up on their phone to receive calls. Thanks to WhatsApp's integration into the iOS contacts infrastructure, it's as easy making a call through the phone app… assuming people still use their iPhones as actual phones.

When you're making a call, WhatsApp gives you some call options. You should be familiar with Mute and Speakerphone, which are features that basically speak for themselves. The other option is Message, which brings you straight into the WhatsApp chat conversation of the person you are calling. It's a simple way to share something like an address or refer back to something said in chat.

3. Tap the status bar to return to the call screen.