[Serusers] Accept invite only for registered users

[Andreas Granig]

sendman wrote:
> Well, I have to check if *calling* are registered on my proxy, before
> to allow him to make any calls!
> 
> In my tests, if a setup on ata186 sipregon=0 so I can make calls, I
> have to block this...

But why do you want to force users to register?

The snippet

   if(method=="INVITE" && !proxy_authorize("your.domain", "subscriber"))
   {
     proxy_challenge("your.domain", "0");
     break;
   }

prevents unauthorized users from placing calls. The registration has 
nothing to do with authorization or something like that, it's just that 
SER knows whom to contact when someone calls the user via the proxy.

Andy