asterisk users - Jul 2007 - allow third party registration/invitaion

Hi all,
I'm running some performance tests  over my Asterisk,to simple the
test,I want to configure Asterisk to allow third party registration
and invitation,so that Asterisk would not check the "to" head when
challenge registartion and "from" head when challenge invitation,and I
can only create one account and register several clients with
different numbers using this account.Does  Asterisk support that?How
to configure?Please advise,thanks a lot.