Creating a VoIP app in React Native - the beginner's guide

VoIP apps such as Zoom, WhatsApp, and Teams connect people over the internet, sometimes without phone numbers. Kwiatek identifies three essentials: access to the microphone or camera, a connection between participants, and a way to show incoming calls through the phone’s native APIs.

Apps need to handle users denying or revoking microphone access, including by explaining what to do next and keeping the app usable. WebRTC can capture media and connect peers, but the connection requires exchanging session descriptions and ICE candidates through a signaling channel, such as a WebSocket service.

Kwiatek describes SIP libraries such as JsSIP and SIP.js as abstractions that handle WebRTC signaling and session management. They require a SIP server, with Kamailio and FreeSWITCH as examples. He recommends starting with pure WebRTC to understand the setup, then considering SIP based on the app’s needs.

Mobile apps need to receive calls while in the background. Kwiatek says iOS apps should use VoIP push notifications for incoming calls and report them through CallKit; Android apps can use notifications and ConnectionService. React Native CallKeep supports CallKit and ConnectionService from React Native.

Kwiatek recaps the need to plan for denied permissions, integrate WebRTC, and decide whether SIP is appropriate for the use case. He also suggests checking whether an existing SDK, such as Twilio, could provide needed VoIP features more cost-effectively than building everything from scratch.