Google Voice - Google Voice gives you one number for all your phones, voicemail organized in an email format, free...

Seald - Keep your conversations secure, everywhere.

TextMe - TextMe is a free calls and messaging application at both local and international levels.

Crypho - End-to-end-encrypted messaging and file sharing

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.

Spike - Spike solves businesses' communication chaos by bringing together email, team chat, collaborative docs, and meetings, into one feed.