Configuring an AVM FritzBox with 3CX
This guide shows you how to configure an AVM Fritzbox router / firewall as a border device with 3CX. This document is based on a FritzBox 7170 with firmware version 29.04.76. Please note that we cannot assist you in the configuration of your firewall.
Note: This document includes screenshots in German as an English language firmware could not be uploaded on the device. Some settings are translated from German to English for ease of reference.
Step 1: Activate Expert Mode on the Router
- Log into the AVM Fritzbox web interface.
- Click on “Einstellunden” (Settings) in the top bar.
- Click on “Erweiterte Einstellungen” (Advanced Settings) / “System” (System) / “Ansicht” (View)
- Check the“Expertenansicht aktivieren” (activate expert view) box.
Step 2: Enable NAT for SIP requests
This option is only available and needed when you use FritzBox in “LAN Mode” and not intended for usage in DSL Mode.
- Open “Erweiterte Einstellungen” (Advanced settings) menu in the AVM Fritzbox web interface, go to “Telefonie” (Telefony) and then the “Erweiterten Einstellungen” (Advanced settings).
- Check the checkbox for “Portweiterleitung des Internet-Router für Internettelefonie aktiv halten” (enable port forwarding of the Internet-Router for internet calls).
- Set the value to 5 minutes.
Step 3: Configure Port Forwarding (NAT)
This example shows port forwarding configuration for port 5062 with 3CX PBX system on IP: 10.172.0.141:
- Open the “Erweiterte Einstellungen” (Advanced settings) menu in the AVM Fritzbox web interface, select “Internet” (Internet), then “Freigaben” (Sharing) and click the tab “Portfreigaben” (port sharing).
- The 3CX SIP port CANNOT be 5060, so 3CX must be installed or reconfigured using a different SIP port. Alternatively you may reconfigure your AVM as documented here.
- Assign the ports for the following protocols:
- HTTP (TCP )
- HTTPs (TCP)
- SIP (TCP/UDP)
- SECURE SIP (TCP)
- RTP (UDP)
- TUNNEL (TCP/UDP)
Note: For an always up to date list of the ports that need to be open check here.
Step 4: Validating Your Setup
Log into your 3CX Management Console, go to Dashboard → Firewall and run the 3CX Firewall Checker. This will validate if your firewall is correctly configured for use with 3CX. More information about the Firewall Checker can be found here.