asterisk users - May 2005 - Asterisk not recognising "On Hold"

I'm having some troubles with my * machine, when i place a call on hold
the callee doesn't hear any MOH and the call is dropped because of lack
of RTP.
I also don't see * starting MOH on the SIP channel the callee is on (moh
class is defined, there are MP3 files and mpg123 is active).

I'm using * 1.0.6 right now with Cisco 7940's, i can see * recieving a
SIP invite with c=0.0.0.0 so that should work, i can allso see the
invite back to the phone when getting the call out of hold. Because of
this problem attented transfers won't work correct either (since the
other side of the call gets dropped before the call is transferred). All
calls are SIP<-->SIP.

Any ideas?

Kind regards,

E. Versaevel