I guess the best point about these is that they are actually (or hopefully?) somewhat standardised - XMPP with OTR works perfectly fine on the desktop, albeit o

I guess the best point about these is that they are actually (or hopefully?) somewhat standardised - XMPP with OTR works perfectly fine on the desktop, albeit only for IM. Inventing a new protocol to provide essentially the same features appears a little unnecessary - at least the IM part could have reused OTR with voice calls using some other encryption (possibly based on the keys negotiated via OTR).