SBC Public IP: 188.8.131.52
SBC Private IP #1: 192.168.1.11 (Connection to ITSP - Public IP Ports Forwarded to this IP)
SBC Private IP #2: 192.168.1.10 (Connection to Switchvox)
Ensure the following ports are open or forwarded to the public IP of the SBC.
- 5060 UDP
- 10,000 to 20,000 UDP
1) Go to Configuration → IP Settings → Access Control List and add a new list called ACL. Ensure the default policy is Deny, and then add both the IP of the PBX, and the IP(s) of your ITSP. Ensure the prefix is /32 to only allow the single IP.
Note: In this case the ITSP is Sangoma's SIP Station. The FQDN's are trunk1.freepbx.com and trunk2.freepbx.com. Check with your ITSP if you need the IPs.