multiple Cisco ATA188's behind a NAT; they can call out but can't call in

["Gerard J. Cerchio" <gjpc@circlesoft.com>]

Greetings all,

I have multiple Cisco ATA 188 phone adapters behind a Debian Woody 2.4 
kernel acting as a NAT to a single Internet IP address.

The phones all make outgoing calls just fine. The incoming calls cannot 
get through.

Does anyone have an iptables NAT script that will allow the phones to 
work both ways?

Here are my current entries:

   iptables -t nat -A POSTROUTING -s $MASQ_NET -o $EXT -j MASQUERADE

   iptables -t nat -A PREROUTING -d $EXTIP -p tcp --dport 16384 -j DNAT 
--to-dest 10.10.0.12:16384
   iptables -t nat -A PREROUTING -d $EXTIP -p udp --dport 16384 -j DNAT 
--to-dest 10.10.0.12:16384
  
   iptables -A FORWARD -i eth0 -p udp -d 10.10.0.12 --dport 16384 -j ACCEPT
   iptables -A FORWARD -i eth0 -p tcp -d 10.10.0.12 --dport 16384 -j ACCEPT

where 16384 is the media port on the ATA188 (there is a set for each ATA188)
the -FORWARD's don't seem to do anything

Thanks,

Gerard J. Cerchio
www.circlesoft.com