Looking for some real privacy, or scared that someone might be snooping in on your calls? then you might need Signal for iPhone.
A software application called Signal, developed by OpenWhisper will enable you to encrypt each and every call you make on your iPhone. A part of the encryption is done using ZRTP protocol which encrypts every conversation. And your call’s metadata will be secured as well.
The software is open-source which means contributors are welcome in funding the project. The team of security researchers are also working on developing another software for encrypting text messages. They have actually been doing a lot of research on security, just last week they released a highly secure cloud synchronization service for Android contacts and calenders.
Signal for Android also seems to be on it’s way, so Android users who would like to have the app should be patient.