[Serusers] Proxy_authorize, www_authorize

What is the difference between these two functions? Also, when it comes to authentication, I've finally got my PSTN secure. It seems that every request that you want guarded must be preceeded by a www_authorize(), right? When I ngrep for the packets going back and forth, I see that each INVITE is now being authorized....not just the REGISTERs. I was assuming that you logged in and were authorized once, and then each request was under that login. However, I see that isn't the case, right??? You *can* make a INVITE request without REGISTERing...right? I'm getting older, this information takes longer to seep in :-) ---greg