How to Set Up a 3CX Phone System: Step-by-Step Guide

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Getting a 3CX phone system up and running is one of the best investments a business can make in its communications infrastructure. Whether you’re replacing an ageing ISDN system, switching from an expensive per-user platform like RingCentral, or starting fresh, 3CX offers enterprise-grade features at a fraction of the cost.

This guide walks you through the entire setup process — from choosing your hosting method to making your first call. We’ll cover the free StartUP plan through to Pro and Enterprise deployments.

Before You Start: What You Need

Hardware / Infrastructure

  • Internet connection — minimum 100kbps per simultaneous call. Standard business broadband handles 20-50+ calls easily
  • Hosting — choose one:
    • 3CX Cloud (hosted by 3CX — easiest)
    • Your own cloud (AWS, Azure, Google Cloud, DigitalOcean)
    • On-premise server (Linux or Windows)
  • IP phones (optional) — Yealink, Fanvil, Grandstream, or Poly desk phones. Or just use softphones (desktop/mobile apps)

Accounts / Services

  • 3CX account — sign up at 3cx.com (free StartUP plan available)
  • SIP trunk — this connects your phone system to the phone network so you can make/receive calls to landlines and mobiles. ITelecoms provides SIP trunking with competitive rates and full 3CX compatibility
  • Phone numbers — either get new numbers from your SIP provider or port your existing numbers across

Step 1: Choose Your 3CX Edition

EditionUsersPriceBest For
StartUPUp to 10FreeSmall offices, testing
SMBUp to 20€175/yearSmall businesses
PROUnlimited€295/yearGrowing businesses, call centres
EnterpriseUnlimited€495/yearLarge deployments, advanced features

StartUP is genuinely free — no credit card, no trial period. It includes voice, video, chat, and mobile apps for up to 10 users. If you’re unsure, start here and upgrade later.

For businesses that need call reporting, wallboards, or Microsoft Teams integration, you’ll need Pro or Enterprise.

Step 2: Install 3CX

Option A: 3CX Cloud (Recommended for Most Businesses)

The simplest option. 3CX hosts everything — no server to manage.

  1. Go to 3cx.com and sign up
  2. Choose your edition
  3. 3CX provisions your instance automatically
  4. You receive a management console URL and admin credentials
  5. Log in and start configuring

Option B: Self-Hosted Cloud (AWS, Azure, etc.)

For businesses that want more control over their infrastructure:

  1. Launch a Linux VM (Debian 12 recommended) on your cloud provider
    • Minimum: 1 vCPU, 1GB RAM (for up to 16 simultaneous calls)
    • Recommended: 2 vCPU, 4GB RAM (for larger deployments)
  2. SSH into the server
  3. Run the 3CX installer: wget -O- https://downloads-global.3cx.com/downloads/debianrepository.sh | bash apt update && apt install 3cxpbx
  4. Follow the web-based setup wizard
  5. Open the required ports in your cloud firewall (SIP: 5060/5061, RTP: 9000-10999, HTTPS: 443)

Option C: On-Premise Server

Same as Option B, but on a physical server in your office. Gives you full control and keeps all voice traffic local. Requires a static IP and port forwarding on your router.

Step 3: Configure Your SIP Trunk

The SIP trunk connects your 3CX system to the phone network. Without it, you can only make internal calls between extensions.

  1. In the 3CX Management Console, go to SIP Trunks → Add SIP Trunk
  2. Select your provider from the dropdown (if listed) or choose Generic SIP Trunk
  3. Enter the credentials from your SIP provider:
    • Trunk name (e.g., “ITelecoms SIP”)
    • Registrar/Server — your provider’s SIP server address
    • Authentication ID — your SIP username
    • Password — your SIP password
    • Number of simultaneous calls — match your trunk capacity
  4. Click OK and wait for the trunk to register (Status should show “Registered”)
  5. Make a test call to verify

If you’re using ITelecoms SIP trunking, we provide pre-configured templates and handle the setup for you.

Step 4: Set Up Phone Numbers (DIDs)

DIDs (Direct Inward Dialing numbers) are your phone numbers — the numbers people dial to reach you.

  1. Go to SIP Trunks → Your Trunk → DIDs
  2. Add your phone numbers (provided by your SIP trunk provider)
  3. For each number, set the Inbound Route:
    • Ring an extension directly
    • Go to an IVR (auto-attendant)
    • Ring a ring group
    • Go to a call queue

If you’re porting numbers from an existing provider, your SIP provider handles the porting process. Numbers typically transfer within 5-10 working days while your service continues uninterrupted.

Step 5: Create Extensions

Each user in your organisation gets an extension.

  1. Go to Users → Add User
  2. Fill in:
    • Extension number (e.g., 100, 101, 102…)
    • First name / Last name
    • Email address (used for voicemail notifications and app login)
  3. Set the extension’s forwarding rules:
    • What happens when they don’t answer (voicemail, forward to mobile, etc.)
    • What happens when they’re busy
    • What happens outside office hours
  4. Click OK — 3CX sends the user a welcome email with their credentials

Provisioning Desk Phones

If you’re using physical IP phones:

  1. Go to Phones → Add Phone
  2. Select the phone model (Yealink T54W, Fanvil X4U, etc.)
  3. 3CX generates a provisioning URL
  4. On the phone, enter the provisioning URL in the phone’s web interface
  5. The phone auto-configures itself — extension, server, codecs, everything

Most modern Yealink and Fanvil phones support zero-touch provisioning via DHCP Option 66 — they pick up the provisioning URL automatically on your network.

Step 6: Set Up the IVR (Auto-Attendant)

The IVR is what callers hear when they ring your main number: “Press 1 for Sales, Press 2 for Support…”

  1. Go to Advanced → Digital Receptionist
  2. Create a new IVR
  3. Record or upload your greeting (3CX also supports text-to-speech)
  4. Configure the menu options:
    • Key 1 → Sales queue or extension
    • Key 2 → Support queue or extension
    • Key 0 → Receptionist
    • Timeout → Voicemail or receptionist
  5. Assign the IVR to your main phone number (go back to SIP Trunk → DID → set route to this IVR)

For businesses exploring AI-powered call answering, ITelecoms offers an AI Receptionist service that can handle calls, book appointments, and route enquiries automatically — integrating with your 3CX system.

Step 7: Set Up Call Queues

If you have a sales or support team, call queues distribute incoming calls evenly:

  1. Go to Advanced → Call Queues → Add Queue
  2. Name the queue (e.g., “Sales Queue”, “Support Queue”)
  3. Add agents (extensions) to the queue
  4. Configure:
    • Ring strategy — Ring All, Round Robin, Longest Idle, etc.
    • Queue timeout — what happens if no one answers (voicemail, overflow to another queue)
    • Music on hold — upload custom audio or use default
    • Callback option — let callers request a callback instead of waiting

For monitoring queue performance in real-time, Advanced 3CX Reports by ITelecoms provides live wallboards showing queue stats, agent availability, SLA metrics, and call volumes — displayed on a TV in your office or on a dashboard.

Step 8: Install Client Apps

3CX has apps for every platform:

  • Web Client — access via browser at your 3CX URL
  • Desktop App — Windows, Mac, Linux
  • Mobile App — iOS, Android

To set up:

  1. Users receive a welcome email from 3CX with a QR code
  2. Download the 3CX app from the App Store or Google Play
  3. Scan the QR code — the app configures itself automatically
  4. Start making and receiving calls

The mobile app works over WiFi and mobile data, so your team can take business calls from anywhere — with the business number showing as caller ID, not their personal mobile.

Step 9: Configure Advanced Features

Call Recording

  • Go to Settings → Call Recording
  • Enable for all calls, specific extensions, or specific queues
  • Recordings are stored on the server and accessible via the web client

Office Hours

  • Go to Settings → Office Hours
  • Set your business hours for each day
  • Configure what happens outside hours (IVR, voicemail, forward to mobile)

Voicemail

  • Enabled by default for all extensions
  • Voicemail-to-email sends audio files to users’ email
  • Users can customise their greeting via the 3CX app

CRM Integration

  • Go to Settings → CRM Integration
  • Connect to Salesforce, HubSpot, Zoho, Microsoft 365, Freshdesk, and more
  • Incoming calls automatically pop the caller’s CRM record
  • Call logs sync to the CRM automatically

Common Setup Issues

“SIP Trunk won’t register”

  • Check your firewall — ports 5060 (SIP) and 9000-10999 (RTP) must be open
  • Verify the credentials match exactly (copy-paste, don’t type)
  • Check if your ISP blocks SIP traffic (some do — switch to port 5061/TLS)
  • Contact your SIP provider to verify the account is active

“Calls connect but no audio”

  • This is almost always a firewall/NAT issue
  • Ensure RTP ports (9000-10999) are forwarded to your 3CX server
  • In 3CX, go to Dashboard → Firewall Check and fix any red items
  • Enable STUN if behind NAT

“Desk phone won’t provision”

  • Ensure the phone is on the same network as the 3CX server
  • Check the provisioning URL is correct
  • Factory reset the phone and try again
  • Ensure the phone firmware is up to date

Frequently Asked Questions

How long does setup take?

A cloud-hosted 3CX system can be operational in under an hour. Add another hour for SIP trunks, extensions, and IVR configuration. With a partner like ITelecoms handling the setup, it’s typically done in a day.

Can I keep my existing phone numbers?

Yes. Number porting is standard. Your SIP trunk provider handles the porting process. Numbers transfer within 5-10 working days.

Do I need desk phones?

No. The 3CX desktop and mobile apps work perfectly as softphones. Many businesses are going phone-free — just headsets and the app. Desk phones are optional for those who prefer physical handsets.

Can I integrate 3CX with Microsoft Teams?

Yes. 3CX supports Microsoft Teams direct routing, allowing your team to make and receive PSTN calls from within the Teams interface using your 3CX system and SIP trunks.

What if I need help with setup?

ITelecoms handles 3CX setup end-to-end — installation, SIP trunk configuration, extensions, IVR, call queues, reporting, and training. We’re official 3CX partners with years of deployment experience.

Ready to set up your 3CX phone system? Contact ITelecoms — we’ll handle the entire deployment so you can focus on your business. Or start with the free 3CX StartUP plan and upgrade when you’re ready.

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