Adding SIP Trunks & VoIP Providers
Zero Admin
With the new Dashboard
Bulletproof Security
With SSL certs and NGINX
Install on $150 Appliance
Intel MiniPC architecture
New, Intuitive Windows Client
More themes, more UC
More CRM Integrations
Scripting Interface to add your own
Improved Integrated Web Conferencing
iOS and Android apps included
Personal Click2Meet URLs

Adding SIP Trunks & VoIP Providers

Configuring a VoIP Provider / SIP Trunk

On this topic

Configuring a VoIP Provider / SIP Trunk


Requirements for using a VoIP Provider / SIP Trunk

Configuring a VoIP Provider / SIP Trunk

Step 1: Create an Account with a VoIP Provider

Step 2: Add the VoIP Provider Account in 3CX Phone System

DID’s and Inbound Call Identification

See Also


VoIP providers “host” phone lines and replace the traditional telco lines. VoIP providers can assign local numbers in one or more cities or countries and route these to your phone system. In most cases they also support number porting.

VoIP providers are often able to offer better call rates because they may have an international network or have negotiated better rates. Therefore, using VoIP providers can reduce call costs. However, be aware that each VoIP call requires bandwidth. VoIP is real time, so it does place a demand on your Internet connection. As a rule of thumb, each call will consume approximately 30-120 kb per second, depending on which codec you use. The document, Bandwidth Overhead over DSL connections, includes detailed information about bandwidth consumption, including  particular codecs bandwidth usage.

3CX recommends using supported VoIP providers. All supported VoIP providers have been tested for interoperability with 3CX Phone System, and are re-tested with each new build. Their configuration templates are also included with 3CX Phone System to allow you to quickly and easily add them. See the list of 3CX Supported SIP Trunk Providers.

3CX Phone System supports two types of VoIP providers:

  • Registration Based – These VoIP providers require the PBX to register with the provider using an authentication ID and password. Most of the VoIP providers pre-defined in 3CX Phone System are registration based.
  • IP Based / SIP Trunk – IP Based VoIP Providers (also known as SIP Trunks) do not generally require the PBX to register with the provider. The IP address of the PBX needs to be configured with the provider, so that it knows where calls to your number should be routed.

Requirements for using a VoIP Provider / SIP Trunk

If you plan to use a VoIP provider, you need to have a firewall/router/NAT device that supports STATIC PORT MAPPINGS. Often routers will perform port address translation, which will cause problems such as one way audio, failing inbound calls and so on. It is also highly recommended that you have an FQDN that resolves to a static external IP. If your external IP changes intermittently, inbound calls will fail. See the Firewall & Router Configuration for details to configure your firewall/router/NAT device.

Configuring a VoIP Provider / SIP Trunk

Step 1: Create an Account with a VoIP Provider

First, you need to have an account with a VoIP service provider. 3CX Phone System supports most popular SIP based VoIP service providers and we recommend using one that has been tested by 3CX as 3CX includes pre-configured templates for these VoIP providers. Go to to see a list of supported providers.

Step 2: Add the VoIP Provider Account in 3CX Phone System

After you have created the VoIP provider account, you will need to configure the account in 3CX Phone System. To do this:

  1. In the 3CX Phone Management Console menu, select SIP Trunks > “Add Provider”

  1. 3CX Phone System will prompt you to conduct a Firewall Test. Frequently, the internet facing firewall sitting between 3CX Phone System and the VoIP provider is not correctly configured or is not able to correctly route VoIP traffic. To check the firewall configuration, it is important to perform a firewall check using the inbuilt firewall checker.

  • Click “Run Firewall Checker”.
  • Ensure that the tests for the SIP Port (default port 5060), and the Audio Port range (default ports 9000-9255) all pass with success. If the firewall check fails, you must go to your firewall and troubleshoot why the test failed.
  • After successfully completing the test, return to the VoIP Provider Wizard.

Note: 3CX does not provide specific firewall configuration support.

  1. Enter a friendly name for this VoIP provider account.
  2. Select the Country that the VoIP provider operates in.
  3. Select your VoIP provider from the Provider drop down list. If the provider is not listed, select “Generic VoIP Provider”, or “Generic SIP Trunk”, (If using a generic provider we will not be able to guarantee that 3CX will work with this VoIP provider), Click “Next”.
  4. The SIP server hostname or IP may be pre-filled. Compare these with the details that you have received from your VoIP provider and check that these are indeed correct. Depending on the VoIP provider that you are using, some fields will be disabled. This means you do not need to change them. Click “Next” to continue.
  5. Now enter the VoIP provider account details. In the External number field, enter the VoIP line number that has been assigned to you. Then enter the Authentication ID/username and password of your VoIP provider account. Specify the number of simultaneous calls your provider allows. Click “Next” to continue. If you are using a SIP trunk, the password will be greyed out, since authentication is done via IP.
  6. Specify how calls from this VoIP provider should be routed. You can specify a different route outside office hours. The routing configured here will take effect when no inbound routing rules are matched.
  7. On the next page, you can optionally configure an outbound call rule, which will be used to route outbound calls through the new provider. This is normally done by routing calls starting with a specific prefix. Enter the dialling prefix in the “Calls to numbers starting with (prefix)” text box. To make calls via this provider, precede the number to be dialled with this prefix.

More about Outbound and Inbound Rules can be found in the Trunk Management Section.

DID’s and Inbound Call Identification

If your VoIP provider has provided you with DID numbers, you will need to specify these in the DID tab. To do this:

  1. In the 3CX Management Console, select SIP Trunks click on the VoIP provider you want to configure.
  2. Click on the “DID” tab.
  3. Add the DID numbers associated with your account. An Inbound Rule, which can be configured at a later stage, will be created for each number specified in this list.

You can also see the list of inbound rules by expanding the “Inbound Rules” node.

More about Inbound Rules can be found in Chapter 8.

See Also



You might also be interested in:

Ask a Question

Please only post questions in regards to the document you are currently reading.
Technical support or pre sales questions must be posted via the support or sales channels and such comments will be deleted. Thank you for understanding

Leave a Reply

  1. Ed Mulder


    How can I add a voip provider into 3CX? I only can chose out of 4 Dutch providers. Or is it not possible in the trial/free version I’m using?
    If so, how can I test my connection with my SIP-provider? Now I’m using Gigaset N300 IP and T-Mobile (gigaset) 501V as well the sip-account of the huawei modem (

    With thanks in advance for your answer,

    Ed Mulder

    August 5, 2015 at 7:52 pm Reply
    • Charalambos Eleftheriou

      @Ed, Thanks for the question. You can add VoIP providers to the free version. The providers in the list for your country are the providers that 3CX supports. We recommend that you use one of these providers. You can use the generic template for an unsupported VoIP provider. However any support issues you will have to take up with the VoIP provider and not with us. We support the Gigaset 510 IP Phone with 3CX, you will find this guide useful :

      August 6, 2015 at 9:55 am
  2. Hi how do I port my current number associated with eircom over to VOIP?
    Also do I need a permanent static IP address

    August 18, 2015 at 1:11 pm Reply
    • Charalambos Eleftheriou

      @Fergus, Thanks for the questions. You can contact your VoIP provider to port your number over. To install 3CX Phone System you will indeed require a static IP Address. Thank you.

      August 18, 2015 at 2:50 pm
  3. Brent A

    is an Authentication ID the same as an Authentication Name as my sip provider calls it. Is an Authentication Password the same as an Authentication key as my sip provider calls it?

    September 3, 2015 at 5:12 am Reply
    • Charalambos Eleftheriou

      @Brent, thanks for the question. That sounds about right. Give it a try.

      September 3, 2015 at 9:04 am
  4. Michael

    Is it possible to use a Baronet card to connect a local piston line to a hosted 3cx pabx ? is this feasible or better to try and port the no.

    November 11, 2015 at 9:39 pm Reply
    • Charalambos Eleftheriou

      @Michael, Thanks for the question. You can use one of our supported gateways to connect your PSTN line with 3CX Phone System. find a full list of supported gateways here: Porting the number of to a VoIP provider and configuring with 3CX is also possible. Contact one of our supported VoIP providers for more details:

      November 11, 2015 at 10:24 pm
  5. How can I hide my caller ID when I make a outgoing call?

    March 8, 2016 at 2:48 am Reply
    • Charalambos Eleftheriou

      @Jiahuai, this is something you need to ask your VoIP provider. They should give you a few numbers to dial before the number you are calling that when used will hide your caller ID.

      March 8, 2016 at 11:11 am
  6. Mike

    I have installed the 3CX 14 on a Windows 10 PC, forwarded all the required port and the Firewall Checker passed. I am using CallCentric (One of your supported VoIP provider) and have configured the SIP Trunk according to their instructions for 3CX, but I CAN NOT get the 3CX to register to my CallCentric account.

    June 14, 2016 at 3:15 am Reply
    • @Mike – Then it is possible you made a mistake in the setup of the provider (the configuration of it). Check all the entries again.

      June 14, 2016 at 10:10 am
  7. Mike

    Nicky, I checked and contacted VoIP provider and they are saying that my 3CX is not making any contacts withe their servers. I also have a Talkswitch IP PBX that I tried with my VoIP provider and it works, but can’t get 3CX to register with them.

    June 14, 2016 at 7:06 pm Reply
    • Mike

      I have solved this issue. When I ran the Firewall Checker during setup, it stopped the Server Services. Once the Firewall Checker is successfully completed, these services must be Restarted. System-Services-Restart All.

      June 26, 2016 at 7:17 pm
  8. Ray B.

    I have just installed the trial version of 3CX v15 on our Windows 2012 server and set up some extensions. Is there a SIP trunk configuration provided with the trial version?

    October 28, 2016 at 12:45 am Reply
    • Charalambos Eleftheriou

      @Ray, Sip trunks need to be added we don’t provide one. You can though find some that offer trail periods so to be able to receive incoming calls to make outgoing calls though you would need to buy some credit.

      October 29, 2016 at 12:11 pm