Firewall & Router Configuration

Introduction

If you have 3CX installed on-premise you need to make changes to your firewall configuration to allow 3CX to communicate successfully with your SIP trunks and apps. This guide gives you a general overview of the ports that need to be opened/statically forwarded on your firewall.

If you have remote IP phones, you need to put an SBC or router phone in front of them. Alternatively we recommend the use of our apps which have an inbuilt tunnel. 

Ports required for your SIP Trunk / VoIP Provider

Ports required for your SIP Trunk / VoIP Provider

Open these ports to allow 3CX to communicate with the VoIP Provider/SIP Trunk and WebRTC:

Ports required for remote 3CX Apps & SBC

To allow users to use their 3CX apps remotely, on Android, iOS or Windows, you need to ensure that these ports are open:

Configuring the ports for remote 3CX clients

PUSH messages are sent by the 3CX System to Extensions using smartphones to wake up the devices for calls. This greatly enhances the usability of the smartphone apps.

Ports required for 3CX Video Conference

To create and participate in web-based meetings, the 3CX-hosted cloud service must be able to communicate with the 3CX PBX and vice versa. To do so, these ports need to be configured:

Configuring Ports for 3CX Video Conferencing

Ports required for Other Services (SMTP & Activation)

A 3CX System connects to various services provided by 3CX in the cloud.

Configure Split DNS / Hairpin NAT

You will need to configure the 3CX FQDN to work both internally on your local network and externally outside of your network (unless you do not want to give access to your phone system from outside the network). 

Disable SIP ALG 

Use a router/firewall without a SIP Helper or SIP ALG (Application Layer Gateway), or a device on which SIP ALG can be disabled.

Run the Firewall Checker

After configuring your firewall, run the 3CX Firewall Checker to verify its configuration!

Step by Step Instructions for Popular Firewalls

Example configurations for popular firewalls:


Revision #1
Created 22 May 2024 19:16:07 by Vox Tandem Admin
Updated 22 May 2024 19:19:05 by Vox Tandem Admin