asterisk users - Dec 2008 - G729 reject call when no more licenses how to?

hi
how i can prevent asterisk  try to make calls using G729 when it don't have
any more licenses?
i want it just reject the call or  something like that.
thanks
David
-- 
(\__/)
(='.'=)This is Bunny. Copy and paste bunny into your
(")_(")signature to help him gain world domination.
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
http://lists.digium.com/pipermail/asterisk-users/attachments/20081211/d73f09d3/attachment.htm