Avoid using NAT where possible. However, some NAT gateways provide an adequate SIP ALG (e.g. Technicolor TG582), and some devices provide NAT that works with the new call server (e.g. FireBrick 2500/2700 and many simple NAT routers). Using a STUN server (e.g. ''stun.aa.net.uk''} is another possible solution. If NAT works, then well done, but if not we cannot guarantee to be able to make it work.
See: [[VoIP NAT]]
=Further VoIP Security=