How to configure our CTS Trunk on 3CX

This article covers how to configure 3CX using our CTS SIP Trunk service


This guide will walk you through the deployment of a Hosted Network SIP Trunk to a 3CX Server so that you can send/receive calls through your existing or new 3CX platform.

To complete this guide you will need:

  • A provisioned Hosted Network CTS SIP Trunk

  • Admin access to your 3CX platform

  • Basic ~ Moderate understanding of the 3CX platform

Note: This guide does not cover all facets of provisioning a CTS SIP Trunk within 3CX, it only covers getting the SIP Trunk configured, ensuring it registers and some minor outbound call routing changes Deployment Steps

Assuming you have gathered all the information mentioned above and have Admin access to your 3CX platform you can follow the steps below to deploy a Hosted Network SIP Trunk.

Step 1. Login to your 3CX phone system

Step 2. Once logged in click on "SIP Trunks" in the menu on the left

Step 3. At the top of the page find the "Add SIP Trunk" button and click on it

Step 4. A new window will appear. choose "AU" as the Country, Select Provider in your Country as "Telstra - SIP Trunk" and use your main number in "Main Trunk No". Click Ok to Save

Step 5. On the page that appears scroll down and adjust the below settings as per the below.

  • Enter name for Trunk = Change it to "Hosted Network SIP Trunk"

  • Registrar/Server/Gateway Hostname or IP = The Domain name provided in the SCA in the format of or Note: You will need to use the domain provided in the SCA

  • Outbound Proxy = Remove this Phrase "[Enter proxy provided to you by Telstra]" and then enable the Auto Discovery

  • Number of SIM Calls = Number of channels you purchased with the SIP Trunk

  • Type of Authentication = Do not require - IP Based

Step 6. On the same page (SIP Trunk) go to the ''Options" tab and look for 1. "Put Public IP in SIP VIA Header" Check the box and then supply the public address of your 3CX that you may find in the 3CX Dashboard.

  1. "Transport Protocol" = Change it from TCP to UDP

Click "OK" at the top of the page once done

Outbound Call Changes

If you don't already have a SIP Trunk configured or aren't too familiar with the outbound call configuration you will need to make some minor adjustments to allow calls to flow outbound correctly.

In the 3CX portal simply go to "Outbound Rules" in the menu along the left side of the page.

Once the next page loads up you should have a default rule called "Outbound", edit this trunk and adjust the settings to match the below

  • Calls to numbers with a length of = 10

  • Route 1 = HostedNetwork - SIP Trunk (Or if you changed the name whatever you specified in the SIP Trunk configuration)

Click "Ok" at the top to save the settings, and then add another rule by clicking on "+add".

Change the settings to match the below. This will allow them to call outbound to their local numbers without adding the area code. Click "Ok" at the top to create the table

  • Rule Name = Stamp Local Prefix to outbound calls

  • Calls to numbers with a length of = 8

  • Route 1 = HostedNetwork - SIP Trunk (Or if you changed the name whatever you specified in the SIP Trunk configuration)

  • Route 1 Prepend = Your area code (e.g. 02 for sydney)

You should now be able to call outbound to local, national and special numbers without a problem. Although you may still need to go through additional configuration to achieve the call flow the customer is after.

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.

Last updated