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What Is 3CX?

3CX Phone System - Wikipedia

3CX is a software-based PBX (Private Branch Exchanged) that is based on the SIP (Session Initiation Protocol) standard.

It enables extensions to make calls via PSTN (Public Switched Telephone Network) or via VoIP (Voice over Internet Phone) services.

The 3CX for Windows and Linux is an IP business phone system that supports standard SIP soft/hard phones, VoIP services, and traditional PSTN phone lines.

This PBX can be accessed and managed via a web-based management console, softphones for Windows and macOS, and smartphone clients for iOS and Android.

The system can be used with either SIP phones, the clients, or a combination of both. It also provides functions such as chat, voicemail to email, fax to email, integrated video conferencing, call conferencing, and CRM integration.

What is a PBX?

A PBX (Private Branch Exchange) is a private telephone network typically used within a company or organization, which lets users communicate internally as well as externally (with the outside world).

It also allows for incoming calls and often many extra features such as call queues and logging. A PBX works with a SIP Trunk to provide communications both in and out of the PBX.

How to install 3CX?

System Requirements:

Supported Operating Systems

  • Linux Debian 9
    • Dedicated server for 3CX
    • There should be NO 3rd Party software like DNS and VPN
  • Microsoft Windows 10 64 Bit (Pro or Enterprise)
  • Microsoft Server 2016, 2012 or 2012 R2 (Preferred is 2016)
    • with complete Windows Update and .Net 4.6.1 required
    • Compatible browsers are Chrome, Edge, and Firefox
    • No 3rd Party software installed
    • Needs to be excluded from the Antivirus for the 3CX folders and network traffic
  • Running as a Local Virtual Machine (3CX Tested Hypervisor Platforms)
    • Microsoft HyperV (Higher than 2008 R2)
    • VMware ESXi (Higher than version 5.0)
    • KVM
    • Citrix XenServer (Higher than version 7.0)

Hardware Requirements

  • Bare Metal, VM, or Cloud Provider
  • For the minimum resource requirements see, “Recommended Hardware Specs for 3CX”.
  • Resources depend on the usage
    • Extension count – Memory
    • Call Recording – Storage size and speed
    • VoIP Provided – Memory (Audio Proxy)

Network Requirements


  • Basic Network knowledge
  • RFC-compliant internal network
    • Restriction of HTTP
    • Restriction of SIP
  • Simple network setup
    • 1 Network Interface
    • 1 IP address
    • Disabled unused network adapters
  • Wired Network Connection


  • Configurable Firewall and knowledge of configuration
  • Internet Access
    • Static IP
    • No HTTP Proxy
    • No SSL Deep Inspection
    • Allowed Outbound Network Traffic that will be used for:
      • Activation
      • Updates
      • Web meeting / Web Conferencing

Linux Installation Guide

  • You can install 3CX ISO on Bare Metal servers and Local HyperVisors.
  • You can use PBXexpress on the following:
    • 1&1
    • Amazon AWS (EC2)
    • Google Cloud
    • Microsoft Azure
    • OVH
    • OpenStack API v2 (Nova)
  • You can use apt-get on other cloud Providers

License Key:

All 3CX installations require a license key and there are 3 types of Licenses:

  • Standard (Queues, Bridges, Reports, 3CX FQDN and SMTP only)
  • Pro (Advanced Reports & Queues, CRM, Hotel and Failover)
  • Enterprise (Standby License)

For more information on the different licenses, see the link below.

When installing a license key, just enter the key on the installation type window.

3CX Domain:

If you need to use a 3CX FQDN, you just need to enter the “Hostname” for installation

Do I need a license with my VOIP package?

A license is needed for all 3CX plans, however, a free license is included with the 3CX Standard plan for a 1-year term. After this time, you can purchase 3CX licenses from one of their partner providers. For more information, please visit the 3CX website.

How many extensions can I use with my VOIP plan?

All 3CX plans allow for unlimited extensions.

For example

Hostname: testinstall

3CX Suffix: (depending on the region)

Your 3CX FQDN will be,

For PBX Ports (Ports are ONLY configurable during installation)

  • Web server Default Ports (Free Port Choice)
    • HTTP – 5000 (Only Local LAN – Based on RFC)
    • HTTPS – 5001 (For Local LAN and WAN)
  • SIP Server – 5060
  • Tunnel – 5090

Internal IP or FQDN

  • If on Managed Network
    • Create A Record
    • Point to Local LAN IP of PBX
    • Then select “Enter your local FQDN”
    • Enter A Record in the PBXconfig tool
  • If on an Unmanaged Network (Router is DNS and DHCP)
    • Just select “Local IP”
  • Internal FQDN
    • It allows you to split DNS setups but requires your own domain
    • It allows Failover setups
    • It requires configurable internal DNS and DHCP servers
  • Router Based Network
    • Just install on Local LAN IP

There is also a Web-Based Setup Wizard that contains the following settings:

  • Phone Extension Length (Default is 3 digits and reservers 30 numbers for system extensions. Note that this will not be changeable once the installation is done.)
  • Administrator Emails
    • Receives updated information, Backup, Restore Progress, and Info and Warnings from the system.
    • Mail Server sends welcome emails, faxes, voice mails, and missed call notifications.
    • Mail servers are 3CX SMTP Server, Custom SMTP, or Mail Providers
  • Timezone
    • OS Timezone will be set when using Linux
    • Manually set System Time when using Windows
    • Default timezone when using IP phones
  • Country
    • Vbox number will be set
    • Allows calls to foreign countries

At the end of the wizard, you will be asked to enter Registration Details. Just enter the required information on the fields. If your key has been activated before, it will automatically retrieve the activation from the server if all the information’s entered.

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