This talk was presented during the React Native EU 2021 - the largest community conference in the world focused exclusively on React Native. Abstract: How to make your mobile... to call? Is it easy to create another Skype or Whatsapp? This talk will walk you through the various aspects of creating "the calling app". Starting with what the VoIP actually is, going through some theory of WebRTC connections, and ending with the CallKit of iOS vs Android way of handling calls with the React Native. It will give you a sneak peek of what is required to make a production app that handles outgoing and incoming calls and what kind of infrastructure you need. The talk is based on the experience taken from the phone app made for sales and support teams around the world. Wojciech is a JavaScript developer, trainer, and mentor. Started commercial programming with Node.js, then switched to front end world to work with mobile lastly. During the past few years went through many JS frameworks and companies building different pieces of software. For many years involved in JavaScript trainings by preparing materials and leading both open-source and commercial workshops. Now bridging the gap between tech and business. Twitter: https://twitter.com/WojciechKwiatek Github: https://github.com/wkwiatek Additional Links: Link to slides: https://www.slideshare.net/WojciechKwiatek3/react-native-eu-2021-creating-a-voip-app-in-react-native-the-beginners-guide Link to the main React Native packages mentioned in the talk: - React Native WebRTC: https://github.com/react-native-webrtc/react-native-webrtc - React Native CallKeep: https://github.com/react-native-webrtc/react-native-callkeep