Teams Phone Setup Guide: Get Microsoft 365 Calling Live in 2026
Why Teams Phone Setup Matters in Your Microsoft 365 Stack
If you're managing Microsoft 365 in your organisation right now, you've probably heard about Teams Phone. It's the built-in VoIP system that replaces expensive traditional phone systems. But setup isn't just plugging in devices and hoping it works. Get it wrong and users can't make calls, emergency routing fails, or you end up with phantom licences draining your budget.
The real pressure is this: cloud calling is now expected, not optional. By 2026, most UK organisations are treating Teams Phone as standard, which means IT people who can configure it properly are in demand. If you're moving from healthcare into IT (or already working in IT), Teams Phone is a skill that directly affects your salary bracket and job security.
This guide walks you through a proper setup that actually sticks. No fluff, no assumptions. Just the steps that matter and the gotchas that catch most people out.
Step 1: Audit Your Licences and Calling Plans
Before you touch a single setting in the admin centre, you need to know what you're licensed for.
Teams Phone calling requires:
Many organisations skip this step and wonder why some users can't dial out. The licence audit is not glamorous, but it's the foundation. Go to the Microsoft 365 admin centre, navigate to Billing > Licences, and pull a report of who has what. Spreadsheet it. Print it. You'll reference this constantly.
If you're short on licences, you can also use Phone System Virtual User licences for call queues and auto attendants, but those are specific to routing traffic, not user calling.
Step 2: Set Up Phone Numbers and Calling Plans
Once you know who's licensed, assign phone numbers and activate their calling plan.
In the Teams admin centre (teams.microsoft.com/admin), go to Voice > Phone numbers. You can:
For each user, you'll assign:
The bulk assignment is faster if you have more than a handful of users. Export a CSV template from the admin centre, fill it with user UPNs and the numbers you want to assign, then upload it back. It takes minutes to do 50 users this way.
One common mistake: assigning a number but forgetting to activate the calling plan licence. The user gets a number but can't ring out. They'll ring you in confusion. The licence assignment and the number assignment must both complete.
Step 3: Configure Call Routing and Auto Attendants
This is where Teams Phone starts to feel like a real phone system.
Most organisations set up an auto attendant (an automated greeting that answers calls and routes them to departments or people). In Teams admin, go to Voice > Auto attendants. Create one with:
Below that layer, create call queues. A call queue is a holding area where calls queue up and are answered by the next available person in a group. Sales teams, support teams, and reception all use these.
Each queue can have:
The routing setup can look complex, but the logic is straightforward. Think of it like a real phone tree, just built in the cloud.
Step 4: Assign Phone Numbers to Teams and Devices
For shared spaces (reception desks, meeting rooms), you may need to assign phone numbers to a Teams device or a shared voicemail account instead of a person.
Go to Voice > Phone numbers, and instead of assigning to a user, assign to a resource account. A resource account is a special non-licensed account that acts like a voicemail drop or call queue agent. This is how you get a central reception number that multiple people can answer.
For physical phones (desk handsets or conference room phones), you'll need to provision them in Teams. Go to Devices > Phones, and register the phone's MAC address. The phone will then download its Teams configuration automatically when it connects to your network.
Step 5: Test, Document, and Hand Over
Before you call it done, test everything.
The last point is critical: users' emergency addresses must be set correctly in Teams. If someone dials 999, emergency services need to know where they actually are. Go to Voice > Emergency addresses, and make sure each user has a registered address that matches their physical location.
Document everything as you go. Create a simple spreadsheet with usernames, assigned numbers, calling plan types, and any special routing rules. When you hand over to other IT staff (or if you move on), they'll thank you.
If you're serious about building these skills for a career in IT, the Microsoft 365 Administrator Programme at SmoothOps 365 covers Teams configuration, licence management, and cloud collaboration in depth. It's a three-month programme designed for people moving from healthcare or other sectors into IT admin roles. You can join the waitlist at smoothops365.com/courses for when the next cohort opens.
Common Gotchas and How to Fix Them
Users can't make external calls but can call Teams colleagues. Check that they have a calling plan licence assigned, not just a Teams licence. A Teams licence alone doesn't include outbound PSTN calling.
Calls drop after a few minutes. This is usually a firewall issue. Teams calling requires specific UDP ports open (mainly 3478-3481). Talk to your network admin or check your firewall rules.
Auto attendant greeting plays but menu options don't work. Make sure the call queue or user the menu routes to actually exists and is assigned a phone number or resource account. If the destination doesn't exist, the call hangs.
Voicemail isn't working. Exchange Online voicemail and Teams Phone voicemail are different systems. Make sure users have the right voicemail policy assigned in Teams, not just an Exchange voicemail box.
Frequently asked questions
Do I need a physical phone system alongside Teams Phone?
No. Teams Phone replaces your old PBX entirely. You can use handsets (Polycom, Cisco, etc.), USB headsets, or just the Teams app on a laptop or phone. Many organisations go entirely softphone and save thousands on hardware.
Can I port my existing business numbers to Teams Phone?
Yes. In the Teams admin centre, go to Phone numbers > Get phone numbers > Port phone numbers. You'll need your original account information from your current provider. The port typically takes 10 to 20 business days in the UK.
What happens if someone calls a Teams Phone number when all agents are offline?
That depends on your routing rules. Usually, the call goes to a voicemail drop or an auto attendant that offers a callback option. You set this in the call queue overflow settings.
Is Teams Phone calling charged per minute or included in Microsoft 365?
Domestic calls within the UK are unlimited with a Microsoft 365 Domestic Calling Plan licence (usually around £3-5 per user per month in addition to the base Microsoft 365 licence). International calls may incur extra charges depending on the country.
Do I need a public switched telephone network (PSTN) connection?
No, Teams Phone is entirely cloud-based. You don't need a traditional PSTN gateway or on-premises equipment. As long as your internet connection is reliable and you've configured your firewall correctly, Teams Phone works out of the box.
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