This is an old revision of the document!
Home: https://opnsense.org/
Documentation: https://docs.opnsense.org
Forums: https://forum.opnsense.org
NAT: https://docs.netgate.com/pfsense/en/latest/config/advanced-firewall-nat.html
Configuring NAT for VoIP Phones: https://docs.netgate.com/pfsense/en/latest/recipes/nat-voip-phones.html
Configuring NAT for a VoIP PBX: https://docs.netgate.com/pfsense/en/latest/recipes/nat-voip-pbx.html
Settings for VoIP: https://support.onsip.com/hc/en-us/articles/204029430-PFSense-Firewall-Settings-for-VoIP
Research before using: