Open WhisperSystem, an open source software group, has launched a free encrypted voice calls app called Signal for iPhone and RedPhone for Android.
The technology uses push notification to initiate calls along with ZRTP, protocol used for encryption for voice communication.
It does not require users to get a new number or create a new password to enable the service.
The software uses privacy-preserving contact discovery to let users access contacts easily and in a secure manner.
Signal is a free and open source platform, which lets developers make changes to the code to improve the software as well.
The company plans to expand its service and bring a unified platform for Android, iPhone and browser, and the company plans to provide support text communication compatible with its encrypted text communication TextSecure for Android.