asterisk users - May 2005 - DIAL with FastAGI and Answer Supervision

Hi!
I'm using FastAGI (agi://) to make some calls. To do the dialing i use
"EXEC DIAL Zap/g1/XXXXXXXX...".
But how can I make "answer supervision" with FastAGI? DIAL command
won't return until call is finished.
Thanks in advance!
--
Daniel