Signal app released video calling feature on Tuesday for both Android and iOS. Signal video call feature implements the support for CallKit on iOS 10 devices, a recently introduced framework that lets users VoIP app integrate tightly with the native Phone UI. Signal is considered the most secure instant messaging app, searching for it on the Internet it is possible to read the Edward Snowden testimony: “Use anything by Open Whisper Systems Snowden says. The Cryptographer and Professor at Johns Hopkins University Matt Green and popular security expert Bruce Schneier are other admirers of the Signal app.”]
Source: https://securityaffairs.co/wordpress/56305/digital-id/signal-video-call.html