CallKit is a native framework for VoIP (Voice over Internet Protocol) apps on iOS, introduced by Apple to allow third-party software to integrate with the system's telephony framework, enabling VoIP calls to behave like native phone calls. This means that VoIP apps can use the system's dialer to make calls, and users can access VoIP calls just like regular phone calls.
However, in May 2018, Apple requested that app developers in the China App Store stop using CallKit due to a request from the Ministry of Industry and Information Technology (MIIT). This move affected WeChat, a popular messaging app that uses VoIP, which had been using CallKit in its foreign versions. As a result, some users had to switch to other Apps.
The crackdown on CallKit has also led to the development of alternative APIs on Android, such as ConnectionService. However, few Apps have adopted this API, possibly due to the fragmentation of the Android ecosystem.
In 2023, WeChat, Version 8.0.34, removed the CallKit feature, leaving users with no choice but to stay on Version 8.0.33. The removal of CallKit has been a major blow to VoIP app users who rely on the feature to make seamless VoIP calls.
On the bright side, a HarmonyOS NEXT version of WeChat will soon support CallKit, allowing users to make VoIP calls with the same ease as native calls. This development is set to revolutionize the VoIP industry, and betters the current iOS ecosystem.