Signal - Fast, simple & secure messaging. Privacy that fits in your pocket.
Google Voice - Google Voice gives you one number for all your phones, voicemail organized in an email format, free...
Skype - Stay in touch with your family and friends for free on Skype. Download Skype today to chat and call on desktop and mobile.
TextMe - TextMe is a free calls and messaging application at both local and international levels.
StealthChat - StealthChat is Encrypted, Private, Secure Calls and Chats on Android and Apple iOS
Talkatone - Android App on. Google Play. Stop paying for cell minutes, texts & landlines; Turn your iPad or iPod touch into a phone; Call/Text even in areas with bad cell coverage; Call/Text when travelling without paying for expensive international minutes.