Installing 3CX Phone System as a Virtual PBX Server
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Installing 3CX Phone System as a Virtual PBX Server

Installing 3CX Phone System as a Virtual PBX Server

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Installing 3CX Phone System as a Virtual PBX Server


Software Requirements

Minimum Hardware requirements for 25 Instances

VMware ESX and Hyper V configuration

Network Setup and Firewall Configuration

No NAT Firewall Configuration

NAT Mode Firewall Configuration

Ports that need to be forwarded

Installing 3CX Phone System as a Virtual PBX Server

Virtual PBX Web URLs

Updating 3CX Phone System Virtual PBX Instances via Service Pack Updates


Migrate Cloud Server v12 to the Virtual PBX Server v14


3CX Phone System 14 can be deployed as on premise server, in the cloud, or as a virtual PBX server for up to 25 virtual PBXs. To run 3CX Phone System as a Virtual PBX Server, the following Software and Hardware specifications are required:

Software Requirements

  1. Windows Server 2012 “R2” 64-Bit. (IMPORTANT: Server core editions are NOT supported)
  2. Microsoft .NET Framework 4.5.
  3. Internet Information Services.
  4. VMware ESX or Hyper V cluster environments No other service whatsoever must installed on this machine! This machine must be dedicated to 3CX Phone System.
  5. Each Virtual Instance is recommended not to exceed more than 4/8 simultaneous calls.

Minimum Hardware requirements for 25 Instances

  1. Intel Xeon CPU – E5505 2.00 GHz (6 - 8  processors cores) or higher.
  2. Memory: 25GB or higher.
  3. Hard disk size: 80GB+ depending on Vbox and Recording Quota
  4. Hard disc throughput: 80MB/s or higher, low latency
  5. Network card: 1Gbit / 10Gbit

VMware ESX and Hyper V configuration

3CX Phone System has been optimised for running within VM environments. In the case of VMware ESX, you do not need to make any changes. VMware ESX works out of the box with 3CX. If running Microsoft Hyper-V, it is important to configure the following:

  • A Static MAC Address
  • A Reliable and accurate time source
  • Integrated Services must be installed

See our Microsoft Hyper-V Configuration Guide for detailed information.

Note: We recommend that you take regular backups of your VMs in order to facilitate a recovery if your server was to fail and get things running again quickly.

Network Setup and Firewall Configuration

3CX Phone System allows for two network topology deployment options:

  • No NAT - no NAT is performed from public to a private network
  • NAT - a firewall / router is between the internet and the PBX which performs network address translation.

Both having their own set of benefits and drawbacks. Full Public means that the server is directly connected to the internet without a firewall in between. This of course eliminates the firewall configuration. For one machine, this is a good solution, but as soon as you scale to multiple servers it might be better to have a firewall device in between the internet and your 3CX Phone System servers.

No NAT Firewall Configuration

In case of “No NAT” it is sufficient to use the built In “Windows Firewall” to secure the machine. You do not need to do anything as the 3CX Phone System Installation will open all the required ports automatically during the installation.

NAT Mode Firewall Configuration

If 3CX Phone System is installed behind a NAT device, ports need to be forwarded. A sample configuration for the PfSense firewall can be found here. This example is based on the pfSense firewall, but you may use any other 3CX documented and tested firewall.

Ports that need to be forwarded

If you are installing behind a NAT / Firewall / Router you will need to open the following ports:

Common Ports to all Instances

  • 3CX Management Console (HTTP & HTTPS) & Presence - 80 & 443 TCP
  • Media Server Range - 54,000 – 65,000 UDP Only

For Each Virtual PBX Instance

Each instance uses 3 ports dedicated to their deployment slot.

Instance 1 - Will dynamically use ports in the range 5000 to 5999. You need to forward:

  • Phone System SIP Port - 5060 TCP & UDP
  • Phone System Secure SIP Port - 5061 TCP
  • 3CX Tunnel Service - 5090 TCP and UDP

Instance 2 - Will dynamically use ports in the range 6000 to 6999. You need to forward:

  • Phone System SIP Port - 6060 TCP & UDP
  • Phone System Secure SIP Port - 6061 TCP
  • 3CX Tunnel Service - 6090 TCP and UDP

Additional Tenants - Follow the exact same pattern in the following ranges:

  • Instance 3 - 7000
  • Instance 4 - 8000
  • Instance 5 - 9000
  • Instance 6 - 10000
  • Instance n - +1000

Installing 3CX Phone System as a Virtual PBX Server

  1. Download 3CX Phone System V14 and run the setup file.
  2. 3CX Phone System 14 Requirements will be displayed, please make sure that you read them and that your system configuration complies. Select “Next” to continue.
  3. The Recommendation window will be displayed, click “Next”.
  4. Read the End User Licence Agreement , accept the terms and continue the setup by clicking “Next”
  5. Choose the install folder, either accept the default or choose your own and click “Next”.

  1. You will be prompted to choose your Installation Mode, choose “Virtual PBX Installation (Multiple Instance)” and click “Next”.

  1. Is your server behind a Public IP without NAT or Public IP behind a NAT device. Make you choice and click “Next”.

  1. You will now need to enter your Static Public IP Address, type it in and click “Next”. Furthermore check that the installation has detected your correct default network card.
  2. Enter your server administrator email address to receive notifications. Click “Next”.

  1. Specify the domain name that will be used for all your 3CX instances.
  2. Fill in the details of your SMTP server, that will be used to send out email notification for all your Virtual PBX Instances. Click “Next”.

  1. In order for all your virtual instances to be SSL Secured, you need to purchase a wildcard SSL certificate so you can import it. A wildcard certificate is required because each instance will have it’s own unique company name but the domain part would be common for all instances. For example: *

    If you do not have a wildcard certificate, 3CX can generate a self-signed certificate for you. Click “Next”.

  1. If you have selected to have 3CX create an SSL certificate, enter your Company Name and specify a password. 3CX will automatically generate a self signed certificate for you.
  • Warning - Self signed certificates are not signed by a trusted certificate authority. Therefore browsers will show a security warning when the web page is accessed. For testing purposes this will suffice but it is not recommended for production use. Click “Next” to continue.
  1. Finally click “Install” to install 3CX Phone System Virtual PBX Server. The installation will take approximately 1 hour and will prepare the server to serve 25 instances.

Virtual PBX Web URLs

The URLs for accessing the Management Console for the respective Virtual PBX Instances are generated automatically in the following format:

For example, if you name one of your instances after a company with the name: “contoso”, and your domain name, as the host is: “”, then the instance URL to access the Management Console of “contoso” will be: “”.

Updating 3CX Phone System Virtual PBX Instances via Service Pack Updates

With the “3CX Virtual PBX Manager” you can check for available updates and update ALL installations.

Open 3CX Virtual PBX Manager from the desktop and click the “Check for updates” button. If any updates are available they will be displayed. If there is an update, simply click the “Update” button to update your installation with the latest Service Pack.

Thats all there is to installing your server, you can now proceed to the Creating and Managing Virtual PBX Instances documentation.


If you need to uninstall your 3CX Phone System it is recommended you take a backup of all your Instances using the procedure outlined in the “Backup Using the 3CX Backup and Restore Tool” section of the 3CX Phone System Virtual Instances Backup and Restore document.

To Uninstall simply open your server's Control Panel and within Programs and Features, highlight 3CX Phone System and Click “Uninstall”.

Migrate Cloud Server v12 to the Virtual PBX Server v14

Follow the Migrate Cloud Server v12 to the Virtual PBX Server v14 guide to successfully move 3CX Phone System v12 Cloud Server tenants to v14 Virtual PBX Server, without changing the respective SIP Ports that are already assigned to the existing v12 cloud tenants to simplify the transition.

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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. Is the 4/8 simultaneous calls a recommendation, software limitation, hardware limitation or SBC limitation. I ask as I have a current 3cx Cloud v12 client with a 32 channel license. Will they be able to use the v14 Virtual PBX? If not, can you bridge multiply virtual PBX instances together?

    June 23, 2015 at 10:14 pm Reply
    • Charalambos Eleftheriou

      Hi Richard

      We have based our hardware recommendations on 4/8 simultaneous calls, this is not a software limit. Bridging from instance to instance is not officially supported, not tested. You are can however perform your own testing once the product is available for download.

      June 24, 2015 at 12:34 pm
  2. Spring

    Can we change virtual instance port from (80 & 443)?

    July 15, 2015 at 10:58 am Reply
    • Charalambos Eleftheriou

      @Spring, The default ports for the Virtual PBX server installation are http 80 / https 443 and can not be changed. Thanks.

      July 15, 2015 at 11:21 am
    • Spring

      Thanks you for your answer. Refer to this document each virtual instance is recommended not to exceed more than 4/8 simultaneous calls so this mean if i use E1 i would use on premises server?

      July 15, 2015 at 11:48 am
    • Charalambos Eleftheriou

      @Spring Thanks again for the questions. Our hardware recommendations are based on 4/8 simultaneous calls per instance when using all 25 instances. If you have the hardware resources available there are no software limits in place to stop you from using a few more. We do though recommend that if you have a need for many more then yes an on premise 3CX Phone System is advisable.

      July 15, 2015 at 11:57 am
  3. jean-michel

    Hi, how to change the domain name?
    I forget to add pbx before my domain name and i need to add it.

    July 19, 2015 at 10:23 am Reply
    • Charalambos Eleftheriou

      @Jean-michel, thanks for comment. Do you want your instances to be named for example, Or If you want the latter then you have installed correctly. If you want the first option then before you add any instances uninstall then install again using your preferred FQDN option.

      July 19, 2015 at 10:47 am
  4. Steve

    So to follow the theme above, although no software limitation is in place, the specs above would support (in your view) 8 calls x 25 sites (or 200 simultaneous calls) we could however have 6 instances with 32 channel license (192 possible simultaneous calls) on the same hardware.

    just want to make sure i understand fully what is being said

    August 20, 2015 at 5:49 pm Reply
    • Charalambos Eleftheriou

      @Steve thanks for the question. The total number of sim calls, that we as 3CX have tested with, is a maximum of 16×25 = 400 sim calls per instance. However if you want to have one PBX with a 32 sim call license, then you should sacrifice 2 instances for this installation. You can though choose not to if you like, as you are hosting the service, you can take the decisions. In which case ensure that you have sufficient bandwidth and power for the amount of simultaneous calls. There are no software restrictions on the simultaneous call licenses you can use. We at 3CX set recommended a limit to 16 sim calls because in our opinion, if you want a larger installation, then it is more feasible to have a standard dedicated installation as opposed to hosted one.

      August 21, 2015 at 12:23 pm
    • Steve

      Thanks for the response, the client we have in mind has multiple offices (5) so hosting the system would be really what we would like to do as no site is really bigger than the other (all with around 10 handsets).

      in your explanation below you are saying we should not do this and dedicate a server on one of the sites to the 3cx system, is this correct ?

      August 21, 2015 at 7:22 pm
    • Charalambos Eleftheriou

      Hi Steve, you can host an instance for your customer using Virtual PBX server for 50 extension providing you have the necessary power on your server to drive it. It is up to you how you decide to do this. Our opinion is that for a large amount of extensions and simultaneous calls a stand alone installation would make more sense.

      August 22, 2015 at 10:03 am
  5. Fonewiz

    Has this version been released or is it still in beta?

    September 2, 2015 at 1:30 am Reply
    • Charalambos Eleftheriou

      @Fnewiz, Thanks for the question. 3CX Phone System v14 has been fully released. It is the same version as the RC release nothing has changed.

      September 2, 2015 at 10:10 am
  6. Steven

    Why cant we change the ports to something else? Most of the clients i have use 443 for their mail server or web servers in place. Now i cant upgrade them to v14.

    September 3, 2015 at 11:57 am Reply
    • Charalambos Eleftheriou

      @Steven, thanks for the question. If you have other services using ports 80 and 443 then you can install 3CX Phone System using Abyss web server. This will then allow you to choose the ports that you prefer to use.

      September 3, 2015 at 12:12 pm
    • Eric

      Could the same thing be done with IIS? Go into the instance/site settings in IIS and edit the Site Bindings?

      October 17, 2015 at 7:36 pm
    • Charalambos Eleftheriou

      @Eric, thanks for the question. 3CX Phone System stand alone installation gives the option to choose the Abyss webserver, where ports can be changed. Installing as a Virtual PBX server requires IIS, the ports can not be changed.

      October 18, 2015 at 12:46 pm
  7. Is there a guide for installing on AWS?

    October 28, 2015 at 1:58 am Reply
    • Charalambos Eleftheriou

      @Phil, thanks for the question. If by AWS you are referring to Amazon web services then there are no specific documents. Also make sure that the servers you are installing on are hosted on either Vmware or hyper V.

      October 28, 2015 at 11:07 am
    • Kirsty Anderson

      Ref ‘If by AWS you are referring to Amazon web services then there are no specific documents. Also make sure that the servers you are installing on are hosted on either Vmware or hyper V’

      Does this mean that v14 could not be run under Linux KVM with Windows Server guest?

      December 20, 2015 at 11:09 pm
    • Charalambos Eleftheriou

      @Kirsty, thanks for the reply. 3CX Phone System is supported on either VMWare or HyperV Virtualization environments.

      December 21, 2015 at 9:34 am
  8. Jeremiah G.

    What are the minimum hardware requirements on a per-instance basis (for vms)? There’s a separate document that references hardware requirements for bare metal depending on call capacity, but I can’t seem to find any info on resource allocation for an ESX VM instance. In this case, it’s just a single 128-call VM.

    January 22, 2016 at 8:41 pm Reply
  9. Gary

    How can i connect my gateway to 3cx instance?

    February 17, 2016 at 10:33 am Reply
    • Charalambos Eleftheriou

      @Gary, thanks for the question. It is not possible to connect PSTN\ISDN gateways to a Virtual PBX server hosted instance unless the server that is hosting the instance is installed within the same internal network as the gateway or by using a VPN connection to the network that the server is installed in so that internal IP address of the gateway can be seen from the server.

      February 17, 2016 at 10:45 am
    • Gary

      Dear Charalambos,
      if i have 3 instances at my site so i have to connect PSTN line at my site then roll out configuration at another customer site?

      February 18, 2016 at 4:53 am
    • Charalambos Eleftheriou

      @Gary, thanks for the reply. To connect a PSTN gateway to 3CX Phone System both have to be, or appear to be (via VPN connections), on the same network.

      February 18, 2016 at 9:42 am
  10. Pug RSA


    Can we install 4.6.1 .net framework as its in-place update ?.

    The Microsoft .NET Framework 4.6.1 is a highly compatible, in-place update for the .NET Framework 4.5.2.

    March 19, 2016 at 7:03 am Reply
    • Charalambos Eleftheriou

      @Pug RSA, it is always a good idea to install the latest Microsoft updates.

      March 21, 2016 at 9:22 am
  11. Sonny Williams

    What is the deal with Instance 5? If we have to open up ports 9000 to 9255 for RTP, then how do we forward ports 9060 and 9090 for instance 5?

    April 27, 2016 at 2:43 am Reply
    • Charalambos Eleftheriou

      @Sonny, The actual RTP ports that need to be opened are for the entire server which are UDP 54000 to 65000. The ports you mentioned are for the standalone single instance implementation that are not relevant here. You need to open and forward ports that relate to each instance from your firewall to the Ip Address of the server including the entire range of the RTP ports. Check you firewall documentation on how to open and forward the required ports.

      April 27, 2016 at 3:59 pm
  12. Chris

    How do you change the Public IP address. I installed in NAT mode and the outside IP address is wrong. It is now grayed out.

    May 10, 2016 at 11:44 pm Reply
    • Charalambos Eleftheriou

      @Chris, To change the IP address of the Virtual PBX server you need to backup all your instances at once using the Virtual PBX Management Tool, delete them, then you will be able to change the IP address. Once changed click revert and then restore all your instances at once.

      May 10, 2016 at 11:49 pm
  13. in the last step; 3CX Virtual PBX Manager, i setup my email but when i test email i get an error

    “failure sending mail – unable to connect to remote server”

    how do i resolve this?

    thanks in advance

    July 2, 2016 at 4:13 am Reply
  14. Marc Nonclerc

    We have recently purchased the 3CX software to install in our office with a 32 channel license. This will be the first install for our vendor and during the demo, we asked if the system could be virtualized on a server. They said that it could but did not mention (or did not know) about the 4/8 simultaneous calls recommendation. I see by early comments here, this is not a software limitation but a hardware recommendation. Your hardware requirements are minimal for a PC as most workstations in my environment exceed those requirements easily. We have just purchased a very well equipped Dell server with terabytes of storage, 64 GB of RAM and dual Xeon processors. Seeing that a PC capable of handling 64 sim calls is only an i3 processor with 4 GB RAM, I’m not understanding why it is not recommended to run the system virtualized on a “bad ass” server. Is there something more to it that I am not aware of? Can you shed some light on this for me please?

    August 4, 2016 at 2:44 pm Reply
    • @Marc From where did you get the info that a virtualized 3CX Server can only handle 4-8 sim calls? This is incorrect and a “bad ass” server (given it is configured correctly and responsibly) can keep going up to even 256 sim calls. (We run this load on our Virtual machines during release launch test runs).
      There is no software limitation related to performance for the number of simultaneous calls. It is purely a licensing restriction which drives the licensing model we chose. Beyond 256 sim calls a physical dedicated machine is required. Maybe you got confused with 3CX Cloud installation which can run 25 separate instances of 3CX PBX on a single server. In this case the recommended amount of sim calls per instance (assuming all 25 instances are used) would be between 16-32 per instance.
      You can check this link for more information.
      In each section you have a category named “Can be Hyper V or ESXi”. Wherever you see “optional”, it means you can choose between physical or virtualized. Let us know if something is not clear.

      August 4, 2016 at 8:57 pm
    • Marc Nonclerc

      Hi Nicky! That is awesome news! I couldn’t imagine why such a robust server would not be able to accommodate our small organization’s phone system. I new it could be done because the case studies on your website indicates any number of larger organizations are doing it. Obviously, some would have dedicated boxes for their systems but some (up to 256 sim calls) might be doing it virtually. Unfortunately, I got this information from the vendor we bought the phone system from. In their defense, these guys have provided excellent copper wire service to another one of our businesses but are out of their element when it comes to virtualizing a system. Apparently they were confused (as you suggested) about the Cloud environment. I quote their email her; “3CX recommends 4/8 simultaneous calls per virtual instance and does not support anything beyond it. Look at the comments section of the virtual instance installation.”. Which brings up another question. Is there some formal training I can take myself as an end user/administrator? I know you have lots of training/videos available is there something along the lines of a course? I believe our company will be purchasing several sets of licensing for their other companies if this runs the way I expect it to and I want to be the go-to authority on it. Also, as an end user, do I get tech support directly from 3CX or do I have to go through my vendor?

      August 5, 2016 at 2:34 pm
  15. Pingback: The Best Virtual PBX Phone Systems For Small (And Large) Businesses -

  16. Ricardo Lobo


    I have a doubt: 3CX v15 don’t have Cloud PBX with multiple instances?

    Thank you.

    Best regards.

    October 8, 2016 at 2:21 am Reply
    • Charalambos Eleftheriou

      @Ricardo, V15 does not have a Virtual PBX server version to host multiple instances in one install but you can install v15 on separate VM’s to host for your clients and with the upcoming release of the Linux version, currently in Beta release, it is even more cost effective. Find the details here:

      October 8, 2016 at 1:26 pm