Configuring NAT for a VoIP PBX

For VoIP there are typically a few components to get right for proper inbound and outbound audio from a local PBX.

1. Port forward entries with firewall rules (Or 1:1 NAT with Firewall Rules)
2. Manual Outbound NAT with a rule at the top set to perform static port NAT on traffic from the PBX (Or 1:1 NAT)
3. On the PBX, ensure it is set properly for NAT with the correct external IP and local subnets defined.