Open Source Kotlin VoIP Software

ARK-phone is a complete replacement for the Phone and Messages apps on Android, with free, end-to-end encrypted internet calls between friends. Share your ARK code, link a friend's code and call as usual: when the other phone is reachable the call goes over the internet free of charge, otherwise the same call goes through your carrier. No account, phone number or e-mail is needed. The audio is encrypted with WebRTC (DTLS-SRTP) and travels phone to phone; a relay is used only when no direct path exists and cannot decrypt anything. The dialer has a full in-call screen, a T9 keypad, recent calls with filters, contacts with favourites, dual SIM and flexible call blocking. As the default SMS app it handles SMS and MMS, including groups, with quick reply. No ads, no analytics and no tracking. Available in 11 languages. Source code, issues and discussions: https://github.com/jrs8205/ARK-phone