asterisk users - Apr 2005 - Question on Asterisk CDR / "In-Network Calling" / MySQL CDR

Hi,
I have the asterisk mysql CDR module/patch installed.   But I believe
that's slightly irrelivant to the question.... but is included for
completeness.

How can I determine from a CDR record (csv by default.. or the mysql
CDR)... if a call was "in-network" that is.. from one phone to
another?    I haven't seen anything other then the DST channel seems
to take the format of SIP/xxx or SIP/xxxxxxx where x is the extension
of the phone.