Actually, I found that they use ZRTP from their website. Phil Zimmerman wrote it and he is one of the SC founders. Wikipedia gives a nice overview: http://en.w

Actually, I found that they use ZRTP from their website. Phil Zimmerman wrote it and he is one of the SC founders. Wikipedia gives a nice overview: http://en.wikipedia.org/wiki/ZRTP http://en.wikipedia.org/wiki/ZRTP