asterisk users - Feb 2004 - Problem with * - Nat - Internet - Nat - X-lite

I have an * server installed inside a NAT that is configured to DMZ the
address of the server.  This means that all traffic is automatically
redirected to *.  When I try to connect from a Windows machine (using X-lite)
that is behind another NAT I connect and looking at the * console I can see
that X-Lite is registering.  The problem is that audio seems to drop out. 
When I dial another extension it rings and the other person can answer the
call, but no audio is heard on either side.

     If I dial the Voicemail menu I can hear the prompt for the password and
then it starts to list the number of voicemails in my mailbox but audio cuts
out.  By watching the console I can see that everything is working, the voice
prompts are being sent and I can press the number for an option.  Every time I
press a number I do get the first prompt and then audio goes out again.

     As far as I can see everything is working correctly.  The same notebook
computer works perfectly when on the same network.  Here is a little snip of
my sip.conf

[general]
port = 5060
bindaddr = 0.0.0.0
externip = (real Internet address)
localnet = 192.168.0.0          ; Internal NETWORK address
localmask = 255.255.255.0       ; Internal netmask
context = (my context)          ; Default for incoming calls

[4002]
type=friend
username=4002
secret=secret
host=dynamic
amaflags=default
accountcode=temp
callerid="Carlos Chavez" <4002>
nat=yes
mailbox=4002

     The other extensions I am trying to call are in the same internal network
as the * server.  Any suggestions?

--
Carlos Chavez
Computer Engineer, CCNA
Corporativo Lacer S.A. de C.V.