Hi to all "monowaller"

I use my monowall to provide wireless to many different unknow users
Most of them want to call with VOIP cellular Phones, softphones, and
IPhones.
Because I dont know them before they connect, I cant make firewall rules
based on there IP.
And It's to hard for them to configure a fixed IP (I want the DHCP to make
his job normaly.)

Is there a way to make some kind of port forwarding to accept multiple
clients on VOIP ports
The problem is that, when more than one VOIP client get connected
it unregister all other users VOIP.

192.168.x.x is my private wifi metwork
10.10.10.x is the public wifi network

 WORKS PERFECT with this config
192.168.5.56 ATA
10.10.10.199 NOKIA

NOT WORKING
192.168.5.56 ATA
192.168.5.57 NOKIA

NOT WORKING
10.10.10.199 ATA
10.10.10.198 NOKIA

Please help

Thank you

Thierry