Microsoft Teams can handle most phone calls, but not all of them — and the gaps matter
Microsoft Teams includes calling features that work for internal calls between team members, calls to outside numbers through the internet, and voicemail. For many small businesses and remote teams, this covers the work they actually do. But Teams is not a complete phone system replacement if you need a physical phone on every desk, a traditional phone number that rings through to multiple people at once, or the ability to keep working during an internet outage. Whether Teams works for you depends on what your current phone system does and what you actually use it for.
The decision comes down to what you are willing to give up. Teams trades reliability and always-on availability for simplicity and lower upfront cost. A traditional phone system (PBX, key system, or hosted service) trades flexibility for may provide uptime and features built specifically for phones. Most businesses find they need one or the other, or a combination of both.
Key Takeaways
- Teams calling works well for one-to-one calls and small group calls over the internet, but requires a stable connection and a computer or mobile device to make or receive calls.
- You can port an existing phone number into Teams through a carrier, but the setup takes weeks and requires a Teams Phone license for each user who needs to make outside calls.
- Teams does not work during internet outages, so businesses that need phones to work at all times should keep a backup system or stay with a traditional phone line.
- A traditional phone system handles multiple calls at once, routes calls to groups, and works without internet — Teams does not do all of this without extra setup and licensing.
- The real cost of switching is not just the Teams license, but also the cost of replacing desk phones, rewiring, and training staff on a different way of working.
What Teams calling can actually do
Teams calling lets you make and receive calls through your computer or phone app using your internet connection. You can call other Teams users for free, call regular phone numbers through the internet (which requires a Teams Phone license), and receive voicemail that shows up as a message in Teams. You can also set up a phone number that people outside your organization can call, and that call will ring in Teams on your computer or mobile device.
For teams that work mostly online and already use Teams for chat and meetings, this is often enough. A salesperson can call a customer from their laptop. A manager can take a call on their phone while working from home. A receptionist can answer calls on a computer instead of a desk phone. The calling happens inside the tool people are already using, which can actually make work simpler. Call history, recordings, and transcripts all stay in the same place as your messages and files.
Where Teams falls short compared to a traditional phone system
A traditional phone system (whether a PBX in your office or a hosted system from a carrier) is built to handle phones as a separate, always-on network. It works when the internet goes down. It can ring multiple phones at once when someone calls a main number. It can transfer calls between extensions without dropping them. It can record calls automatically. It can handle dozens of simultaneous calls without slowing down. Teams does none of this without workarounds, and some of it not at all.
The biggest practical difference: Teams requires an internet connection. If your internet goes down, you cannot make or receive calls. A traditional phone line works on a separate network and keeps working. For a business where phones are critical — a medical office, a law firm, a customer service center — this is a real problem. You would need to keep a backup phone line anyway, which means you are not actually replacing your phone system, just adding to it.
The second difference is how calls are answered. In a traditional system, you can set up a main number that rings on multiple phones at once, and whoever picks up first gets the call. In Teams, a call to your Teams phone number rings on one person's device. You can set up call forwarding or a call queue (which requires extra setup and licensing), but it is not the same as a physical phone system where the receptionist's desk phone is the hub. Call queues in Teams also require someone to actively manage them, whereas a traditional system handles this automatically.
What you need to buy to make Teams calling work
If you already have Microsoft 365 subscriptions, Teams is included. But to make calls to regular phone numbers (not just other Teams users), you need a Teams Phone license for each person who will make outside calls. This license costs extra per user per month, and the price varies by region and subscription plan. You also pay separately if you want features like call recording, call queues, or an auto-attendant (a system that answers calls and routes them automatically).
You also need a phone number. You can get a new Teams phone number from Microsoft, or you can port an existing number from your current carrier. Porting takes two to four weeks and requires paperwork from your current carrier. Once the number is in Teams, calls to that number ring on the person's computer or phone app — not on a desk phone, unless you buy a special Teams-compatible desk phone.
If you want desk phones, you have options. You can buy Teams-certified phones (made by Poly, Yealink, and others) that plug into your network and work like traditional desk phones but run Teams software. These phones cost $150 to $400 each. Or you can use softphones — the Teams app on a computer or mobile device — which costs nothing extra but means people take calls on their laptop or phone instead of a dedicated handset. Many businesses use a mix of both.
The hidden costs of switching from a traditional system
The license cost is only part of the picture. If you currently have desk phones, you will need to either replace them with Teams phones or train staff to use the Teams app instead. If your office is wired for a traditional phone system, you may need to rewire for network phones or accept that people will use their laptops and mobile devices. If you have a phone system with features like automated attendants, call recording, or call queues, you will need to rebuild those in Teams, which requires technical knowledge or help from a consultant.
You also lose the separation between your phone network and your data network. A traditional phone system is isolated — if someone hacks your email, they cannot intercept your calls. With Teams, all calls go over the same internet connection as your email and files. This is not necessarily a problem if you have good security, but it is a change in how your business works. Some industries (healthcare, finance, law) have specific requirements about how calls must be handled, and Teams may not meet them without extra configuration.
When Teams makes sense as a phone system
Teams works best for businesses where most people work remotely or in small offices, where calls are not mission-critical, and where people are already comfortable using their computers and phones for work. A software development company, a consulting firm, a small marketing agency — these kinds of businesses often find that Teams calling is simpler and cheaper than maintaining a separate phone system. The learning curve is low because people already use Teams every day.
Teams also works well as a supplement to a traditional system. You can keep your main office phone system and add Teams calling for remote workers or branch offices. This gives you the best of both: a reliable phone system where you need it, and flexible calling for people who work from home. Many businesses use this hybrid approach for years without ever fully switching.
Teams does not work well if you need phones to work during internet outages, if you have high call volume with many simultaneous calls, or if you need advanced features like automatic call recording or complex call routing. In those cases, a traditional phone system or a hosted phone service (like Vonage, 8x8, or RingCentral) is a better fit. These services have their own networks and do not depend on your internet connection.
How to test Teams calling before you switch
If you are considering Teams as your phone system, start small. Set up Teams Phone for a few users and have them use it for a month. See whether they actually use it, whether the call quality is good, whether they miss having a desk phone, and whether your internet connection is stable enough. Ask them what they like and what frustrates them. This real-world test will tell you more than any comparison chart.
Also test what happens when your internet goes down. If your business can survive without phones for an hour or two, Teams might work. If you need phones to work at all times, you need a backup — either a traditional phone line or a second internet connection. Many businesses discover during this test that they need more reliability than Teams can provide, and that is valuable information before you commit to a full switch.
Frequently Asked Questions
Can I keep my current phone number if I switch to Teams?
Yes. You can port your existing phone number from your current carrier into Teams. The process takes two to four weeks and requires your current carrier to release the number. Once it is in Teams, calls to that number will ring in Teams on your computer or phone app. You will need a Teams Phone license for the person who receives those calls.
What happens to my calls if the internet goes down?
Calls stop working. Teams calling requires an internet connection. If you need phones to work at all times, you should keep a traditional phone line as a backup, or use a phone service that has its own network separate from your internet connection.
Do I have to use desk phones with Teams, or can people just use the app?
You can do either. People can make and receive calls using the Teams app on their computer or phone, with no desk phone at all. Or you can buy Teams-certified desk phones that plug into your network. Many businesses use a mix — desk phones for people who are in the office most of the time, and the app for people who work remotely.
Is Teams calling find?
Teams calls are encrypted, but they travel over your internet connection along with your email and files. If security is a concern, talk to your IT team about whether Teams meets your organization's requirements. A traditional phone system is isolated from your data network, which some businesses prefer for security reasons.
How much does it cost to switch to Teams calling?
The cost varies widely depending on how many people need calling, whether you keep your current phone number, and whether you buy desk phones. A Teams Phone license costs a few dollars per user per month. Desk phones cost $150 to $400 each. Porting a phone number is usually free or a small one-time fee. The biggest cost is often the time and effort to set it up and train people to use it differently.