Encrypted voice is very tricky to get right. One of the state of the art open protocols is SRTP (and ZRTP). However, outside of Signal and a few others, a fair

Encrypted voice is very tricky to get right. One of the state of the art open protocols is SRTP (and ZRTP). However, outside of Signal and a few others, a fair amount of e2e encrypted voice is proprietary and aimed at the defence market. Webrtc (including p2p) is also encrypted, but it’s not e2e unless the calls are p2p. One channel for information leakage is variable bitrate codecs. Have a look at this paper. http://www.cs.jhu.edu/~cwright/voip-vbr.pdf http://www.cs.jhu.edu/~cwright/voip-vbr.pdf