asterisk users - Mar 2006 - remote IP address in channel?

Hi,

when I get a SIP call from an unknown user, I can
see the IP address in the channel name.

When the call comes from a known user (sip friend),
I can see only the username in the channel name.

Ok, most users will use the IP address, which they also
register, thus can be lookup up in the registry.

But I'm looking for a reliable channel variable or any reliable mean,
where a SIP call from a known user really comes from.


Any ideas?


Roger.