asterisk users - Sep 2004 - SIP peers in MySQL Database and accountcode lack

Hello!

Checking chan_sip.c sources and `sipfriends` DB table structures I found 
that there in no "accountcode" support for users.

Is there a way so that I can, through and AGI script, associate a SIP 
inbound call to the right sipfriends account? (I have seen that the 
caller id is in the form of
   "LocalLoggendOnUserName" <name_defined_in_sipfriends>.
Is this spoofable?

Regards,
    Francesco