I am working on this very thing. We will be using LPC encoding for compression, IDEA for encryption, and DH key exchange for key handling. We plan to use something better than DH ASAP (something less vulnerable to man in the middle attacks). We plan to use 14.4kbps transmission speed. Lance, I'd be interested seeing the protocol that you plan to use. I've given a bit of thought to it, and it appears to me that the protocol should negotiate *everything* up front. This would include data rate, xmit and recv speech coders, as well as crypto algorithm, feed back modes, session keys, etc. I've been thinking also that the protocol should start out in async mode, and then possibly shift to sync mode. It should also be extensible. Eric Blossom