asterisk users - Jan 2004 - Unavailable versus private in extensions.conf?

Hi

I'm using an X101P as a Asterisk based answering
machine and it works great.  Thanks.

Is there a way to differentiate a caller ID of
"private" versus "unavailable" in the extensions.conf
file?   I can not find anything in the docs that
says it or isn't possible.

thanks in advance,
Bob Smith