[Serusers] encryption on authorization

Hi there,

In a REGISTER case there is a HeaderField AUTHORIZATION. The usual encryption algorithm is "MD5".

Is it possible to REGISTER without any encryption?

Please give a statement if I understood everything right or correct me:

Digest Username => not encrypted; realm =>not encrypted; URI =>not encrypted;

Nonce => encrypted => is Password? Response => encrypted => what´s that?

Thanks!

P.S.: I sniffered the network traffic when I registerd,established a VoIP-Connection and ended my call. Etherreal, the snifferprogramm, does understand SIP and SDP so I could easy protocol and understand what was going on.