asterisk users - Aug 2004 - chan_h323 doesn't pass audio before call is answered

Hi,

I have the following topology:

PSTN/H323 gateway->GNUGK->chan_h323/chan_sip->SIP EP

Mostly everything works fine except chan_h323 is not passing
audio from PSTN before the call is answered and as a result users
can't hear PSTN announcements (like "the number is not in
service")
that's played on unanswered call. All they hear is just continuous 
ringtone as though remote phone is ringing but noone answering.
I confirmed that gateway (Lucent MAX TNT) and GNUGK is not a problem 
because I can hear those announcements on another h323 endpoint 
registered directly with GNUGK.
Also it did work with previous versions of asterisk (up to 0.9.1) with
some 3d-party patch downloaded at some point from bugtracker.
Now the patch cannot be correctly applied to asterisk-1.0-RC2 and
my attempts to manually apply it failed.
Therefore I would like to request some help on solving this issue.
Does it work for anybody? May be with different PSTN gateway?
Do you have any suggestions on fixing it? 

In addition as we are considering to get some Cisco PSTN/SIP gateway, I would
like to ask if it's also the issue with SIP driver?

Thanks a lot,
Michael