Microsoft Teams Phone is the part of Microsoft 365 that turns Teams into a business phone system. With it, your staff make and take ordinary telephone calls, on your business numbers, from the Teams app on a laptop or mobile or from a desk phone, with call queues, auto-attendants and voicemail handled in Teams.
Calls between Teams users in the same business already work without it, and never touch the phone network. Teams Phone is what you add when you want Teams to replace the phone system: calls to and from any number, inside and outside the business (Microsoft Learn: What is Teams Phone).
What you are buying
You buy two things, and the second is the one that gets missed.
A Teams Phone licence for each user. The licence switches calling on for that person: a dial pad, call transfer, hold, voicemail, and the right to be reached on a phone number. Each user who makes or takes outside calls needs a Teams Phone Standard licence, or a Microsoft 365 plan that already includes Teams Phone. Some enterprise plans do; most business plans do not, so check your licence list before you count on it. Auto-attendants and call queues run on resource accounts, which Microsoft licenses separately from users.
A connection to the phone network. A licence on its own cannot ring a phone number. Microsoft describes the two parts plainly: the licence “entitles a Teams user to enhanced calling capabilities” and the PSTN solution “provides a customer’s tenant with phone numbers and PSTN access”. The PSTN is the public phone network, and something has to connect Teams to it.
The four ways Teams connects to the phone network
Microsoft supports four, and a business can use more than one at once (Microsoft Learn: PSTN connectivity options).
| Option | Who provides the numbers and the calls | What it suits |
|---|---|---|
| Microsoft Calling Plan | Microsoft is the operator; you buy calling plan licences | A business that wants everything from Microsoft and the simplest set-up |
| Operator Connect | A certified phone operator you contract with, enabled from the Teams admin centre | A business that wants an operator but manages numbers in Teams |
| Teams Phone Mobile | A certified mobile operator; the user’s mobile number is also their Teams number | Mobile-first staff who want one number on the handset and in Teams |
| Direct Routing | Any operator, connected through a certified session border controller | A business that needs an existing provider, existing kit or the most flexibility |
We connect Teams through Direct Routing, to our own telephony platform. Your numbers ring in Teams, calls go out showing the business number, and the people who look after the connection are the engineers at our service desk in Stockton-on-Tees. Microsoft’s own calling plans are simpler to buy; the trade is that nobody local answers when something goes wrong, and you have no say in how your numbers are handled.
Keeping your numbers
Customers know your numbers, so the numbers move with you. They are ported into Teams through Direct Routing on an agreed date, and until then the current lines keep working. Porting usually takes 10 to 20 working days for single numbers, longer for ranges and multi-line numbers.
The step before porting matters more than the port itself. Every line and number you have today gets listed, with where it goes and who answers it: the main number, the direct dials, the fax, the number on the van. Only what is on the list moves. The audit also finds the lines that cannot move to Teams at all: the alarm, the lift and the card terminal each need their own digital replacement.
Who still needs a desk phone
Nobody has to have one. Calls work in the Teams app on a computer or a mobile, with a headset if the person wants one. Reception, the warehouse, the workshop and the boardroom usually do want a handset, and Teams-certified desk phones work the same way as the app: the same number, the same queues, the same voicemail.
Part of the business can also stay off Teams. Teams Connect lets Teams users and extensions on an Odyssey phone system call each other, so the office can move to Teams while the warehouse keeps the handsets it relies on, without running two separate phone systems.
How a call reaches the right person
A phone system move fails most often here, because the licence was bought and the call flows were never designed. In Teams, an auto-attendant answers the main number and offers the options, call queues ring a team in the right order, opening-hours rules decide what happens at six o’clock, and voicemail catches the rest. When the flows are designed with the people who answer the phone, the sales line rings the sales team in order instead of one person’s laptop.
A customer team that needs more than queues, with the caller’s record on screen as the call arrives, is a contact centre in Teams with Microsoft Dynamics integration, which is a separate service.
The internet connection
Every Teams call runs over your internet connection. If the line already struggles on a Monday morning, that comes first. For most offices business broadband copes; where everything in the business depends on the connection, a leased line gives dedicated capacity and a contracted fix time. Either way, a 4G or 5G backup keeps the phones ringing when the line fails, because with Teams Phone the phones and the internet are the same thing.
What it costs
Three charges, none of which we publish as figures because they depend on your users and your calling: the Teams Phone licences per user from Microsoft, call charges on an inclusive minute bundle or per minute, and any Teams-certified handsets, bought or on a monthly charge. A move from a separate phone system usually ends one line rental and one maintenance contract, so compare the whole bill, not the licence.
When Teams Phone is the wrong answer
Teams Phone suits a business whose staff already live in Teams all day. If most of your people do not, or if the phone is the job (a busy reception, a trade counter, a workshop), a hosted phone system with proper handsets, such as Odyssey Voice, is simpler and the people using it will thank you. Many businesses end up with both, joined by Teams Connect.
Whatever you choose, the ISDN and analogue lines are retired on 31 January 2027, so a phone system that still depends on them has to move anyway. Our PSTN switch-off check shows what in your building still runs on the old network, the alarm and lift lines first.
Moving to Teams Phone with us
We are a Microsoft partner and have been business telephony specialists since 1987. We audit the lines, assign the licences alongside your Microsoft 365, connect Direct Routing, design the queues and attendants with your team, port the numbers on an agreed date and supply the handsets for the people who want them. Afterwards the same service desk that manages your tenant handles calling questions and new starters, answered within three rings.
We do this for businesses across the North East, including Stockton, Middlesbrough, Newcastle and Sunderland. See our Microsoft Teams calling service, read what to check before you move your phones to Teams, or call us on 01642 661888.