Silent Circle

Silent Circle is an encrypted communications firm based in Le Grand-Saconnex, Switzerland. Silent Circle provides multi-platform secure communication services for mobile devices and desktop. Launched October 16, 2012, the company operates under a subscription business model. The encryption part of the software used is free software/open source and peer-reviewed. For the remaining parts of Silent Phone and Silent Text, the source code is available on GitHub, but under proprietary software licenses.
Source: https://en.wikipedia.org/wiki/Silent_Circle_(software)