RedPhone (for Android) works fine without GSF installed. It just falls back to using SMS instead of GCM for the call signaling. TextSecure, at least the current Android version, also works without GSF, because SMS is…
Moxie Marlinspike's TextSecure. https://play.google.com/store/apps/details?id=org.thoughtcri... https://github.com/WhisperSystems/TextSecure/ Pros: Open source, written by someone well established as being both…
RedPhone (for Android) works fine without GSF installed. It just falls back to using SMS instead of GCM for the call signaling. TextSecure, at least the current Android version, also works without GSF, because SMS is…
Moxie Marlinspike's TextSecure. https://play.google.com/store/apps/details?id=org.thoughtcri... https://github.com/WhisperSystems/TextSecure/ Pros: Open source, written by someone well established as being both…