#7 RedPhone & TextSecure
RedPhone is an Android App that provides end-to-end encrypted phone calls, and secured private conversations. The app blends in with the phone’s dialer and when the call is made or received from another RedPhone user, it asks for permission to encrypt the call.
TextSecure is yet another Android App which provides encryption for SMS and MMS messages exchanged between two TextSecure users.

#6 Elastix
Elastics is a open source software that establishes unified communication by incorporating all communication alternatives to provide an unique solution. It includes a Web GUI for easy configuration of the Asterisk server and all of its extensions and components. This software also supports faxing, video phone calls, UC integration of mobile phones, headsets via Bluetooth, IM features, calendar and contacts and call recording.

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