asterisk users - Jun 2007 - Forward to my phones the domain of the CALLERID in incoming URI calls

Is there a way I can forward to my phones the domain of the CALLERID in 
the CALLERID(number) field of INVITE messages, when some call arrives to 
my Asterisk?

What happens in my architecture is this:

            INVITE  john at our_mydomain
INVITE john at phone's_IP
------------------------------------------------------->     
Asterisk     
------------------------------------------------------------------->     
john's_phone
    From: "Mary" 
<sip:mary at caller_domain>                                        From: 
"Mary" <sip:mary at asterisk's_IP>


As shown, Asterisk substitutes the domain of the caller contact in the 
 From field of INVITE messages that are sent to the destination phone by 
Asterisk's IP address. That way, our phones just display "Mary"
and
"mary" when I want them to display "Mary" and "mary at
caller_domain", so
that john can be aware that Mary is from an outside domain.

Any ideas? How should be my extensions.conf so this can be possible?



Regards,
Ricardo.