WhatsApp allows you send and receive text messages, multimedia content such as audio, video, and images, and lets you make free voice and video calls right from your device.
Twitch is an app that lets you have chat and high-quality voice and video calls with your friends and families for free. The app is inclined towards gamers but it works just well for other users, too.
Linphone is a free and open source VoIP project that allows you to make really high-quality voice and video calls, send instant messages, and do tons of other things to stay in touch with your colleagues.
Signal allows you to send private texts and make calls from your compatible devices without worrying about any privacy matters as it’s completely secure and safe app for instant messaging.
Ring allows you to communicate with others using the most secure environment available. The app respects your freedom and privacy and helps you have secure chats with your buddies on your Windows, Mac, Linux, or Android device.
Jitsi is a powerful and open source community driven video conferencing program that lets you host your important meetings in a safe and secure environment on your compatible devices.
What distinguishes Tox from other VoIP apps is its ability to help users send and receive encrypted communications such as text messages, voice calls, video calls, screen sharing, and file sharing.