Resolving Call Quality issues on 3CX deployments

This article covers how to resolve the issue on audio in 3CX if its hosted in a Cloud Platform


When deploying a Hosted Network SIP Trunk to a 3CX platform you can occasionally encounter call quality issues when one or more lines are active on the system, typically this is caused by latency or issues with outbound connectivity.

To confirm if it issues with outbound connectivity you can follow the process below to run a self-test to check if 3CX can get out to the web on all required ports, if there are any issues with the ports it will highlight them in RED.


This guide will run you through the high-level process on how to run the self-check test for the firewall on the 3CX PBX, this will work for both on-prem and cloud hosted deployments (e.g. AWS, Azure, etc).

To complete this process you will need access to the below:

  • Admin access to the Cloud Hosting platform (if cloud hosted), or

  • Admin access to administer firewall rules on the router in front of the 3CX PBX

  • Admin access to the 3CX PBX itself

Step 1. Login to your 3CX deployment and navigate to the firewall to run the self-check tests.

Login to 3CX and then navigate to the below path (reference screenshot below) "3CX Dashboard" > "PBX Status" > "Firewall"

Click 'Run" then 3CX will check automatically start the self-check tests to confirm if all traffic can get to the required destinations and ports.

Once the test completes 3CX will display a list of all the services and ports, review the list and if you see any errors you will need to go into your Firewall configuration on your Cloud Platform or router to open the recommended ports.

Below is a link to the ports from 3CX official documentation:

Ideally you want all the RTP ports to be opened, or at least partially open.

Step 2. Re-run the checks and re-test the issue

Once you've fixed any issues with the firewall re-run the tests for the firewall check as per step 1 and confirm if any errors appear. You may require to do more than just opening outbound ports, you may need to set the outbound NAT to static instead of dynamically opening ports so that it doesn't change the port to something else.

If the test passes all tests then re-test the call quality issues, if they still persist please reach out to our support team.

If you encounter any issues with this guide or have any questions please don't hesitate to reach out to our support team via email at or via phone on 1300 781 148.

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