KNCTR is described as 'Unlimited free calls anywhere in North America!' and is an app in the Social & Communications category. There are more than 25 alternatives to KNCTR for a variety of platforms, including Android, iPhone, Online / Web-based, Windows and Mac. The best alternative is Wire. It's not free, so if you're looking for a free alternative, you could try WhatsApp or Hangouts. Other great apps like KNCTR are Zulip (Free Personal, Open Source), Whereby (Freemium), aTalk (Free, Open Source) and Daily Co (Freemium).
Daily is an audio and video API. Easily build video chats in your web or mobile apps with an API built on top of WebRTC or drop in the Prebuilt UI for fast video conferencing integration. 1,000 person video and audio calls. HIPAA compliant.
Fully open source instant messaging server and clients. No proprietary components or non-free dependencies. Backend in pure Go (GPL 3.0), with a command-line administration tool in python + gRPC. Clients for Android, iPhone, and Web - ReactJS (all licensed under Apache 2.0).