asterisk users - May 2004 - Zaptel, analog phone, and call waiting

In the docs for the zapata.conf file I see a setting called call 
waiting, presumably for giving the call-waiting beep to an analog phone 
rather than just returning immediately from Dial() with a return value 
of 0 and the priority increased by 101.

In short, I would like to:
Rather than catch a busy line after an immediate return from Dial() I 
would like Dial() to give a call-waiting beep and callerid to the phone 
so we can decide if we want to dump the current call for the incoming.

Searching the wiki and the web didn't turn anything up for me...

Thanks!
-Michael