Integrating Your Phone System with Microsoft Teams: A Practical Set-Up Guide (UK 2026)

Quick answer

Integrating a phone system with Microsoft Teams means giving Teams users a real UK phone number and connecting Teams to the public telephone network, so external calls ring in Teams and staff dial out from it. In practice there are three routes - Microsoft Calling Plans, Operator Connect and Direct Routing - and a fourth pattern that most businesses actually end up with: a hosted phone system for reception and call-heavy teams, Teams Phone for everyone else, with calls transferring cleanly between the two. The set-up itself is a project of two to five weeks: licence audit, route choice, number porting, building queues and attendants, enrolling desk phones, and configuring 999 location information before go-live. This guide is the practical sequence; the strategic comparison of the three routes is in Microsoft Teams Phone for UK businesses.

We support both Microsoft 365 and telephony and build these integrations regularly. If you would rather have it designed and set up than follow the steps yourself, get a no-obligation quote.

Before you start: decide the design

The most expensive mistake is integrating Teams without deciding who should be on it. Sort staff into three groups:

1. Knowledge workers who make and take a few calls a day between meetings. Teams Phone suits them well.
2. Call-heavy roles - reception, sales, support - who need a console, queues with real reporting, and often recording. These usually belong on a hosted telephony platform.
3. Shared and odd devices - the warehouse phone, door entry, a fax - which need a hosted device licence or an analogue gateway, not Teams.

Groups two and three are why the common outcome is a hybrid: hosted for the front of house, Teams for the office, connected so a receptionist can transfer to a Teams user and vice versa. If everyone is in group one, a pure Teams deployment is fine.

The three routes, in practical terms

Operator Connect is the default recommendation for most businesses under a few hundred users, and it is also the easiest way to connect Teams to an existing hosted system, because many hosted providers are Operator Connect carriers or partner with one.

Step 1: licence audit

List Microsoft 365 plans by user. Teams Phone is an add-on to Business Basic, Standard and Premium and to E1 and E3; it is included in E5 and in Microsoft's bundled Teams Phone with Calling Plan licences. Decide who needs a full phone (licence plus route) and who only needs to make the occasional call, and note anyone who will stay on the hosted system. This audit typically reduces the seat count and the cost noticeably.

Step 2: numbers

Decide which numbers go to Teams and which stay on the hosted platform. Main numbers, reception DDIs and any number that feeds a queue with recording usually stay hosted; personal DDIs for office staff move to Teams. Port under Ofcom's rules to Microsoft (Calling Plans) or the carrier (Operator Connect / Direct Routing) - the process in number porting explained applies. Agree the port date around the pilot.

Step 3: connect the route

• Calling Plans: assign Teams Phone and Calling Plan licences, assign numbers in Teams admin. Done.
• Operator Connect: in the Teams admin centre, open Operators, select the carrier, accept their terms, and the carrier provisions the connection. Ported or new numbers appear in Teams admin for assignment.
• Direct Routing: deploy the SBC (AudioCodes, Ribbon or a hosted SBC service), pair it with the tenant, connect SIP trunks from the provider, and build voice routes, PSTN usages and dial plans. This is the route where you want a partner who has done it before.

Step 4: build the call handling

Teams provides two resource types, both free to license as resource accounts: auto attendants (menus, hours, holidays) and call queues (ring groups with music and overflow). Build them to mirror what your business actually does - see the auto attendant guide for the design principles. Set voicemail policies, caller ID rules (show the main number, not personal DDIs, on outbound), and holiday schedules. If reception stays on the hosted system, configure the transfer path between the two so a hosted receptionist can transfer to a Teams user by name and a Teams user can transfer back to a hosted queue.

Step 5: devices

Most staff use the Teams desktop and mobile apps with a headset; certified USB and Bluetooth headsets are worth the money. For anyone who wants a handset, Teams-certified desk phones (Yealink, Poly, AudioCodes) enrol through Teams admin. Existing SIP desk phones from a hosted system are not Teams-compatible without a gateway, which is another reason reception often stays on the hosted platform where its phones already work.

Step 6: recording, if required

Teams' built-in recording is for meetings and does not meet regulatory requirements. If your business needs compliance recording, either add a certified third-party recorder for Teams or keep the regulated team on the hosted platform, where recording is a per-user policy. Our guide to call recording for compliance covers what the rules require.

Step 7: emergency calling

Configure 999 location information for every office and set up dynamic location for remote and mobile workers. In the UK this is a regulatory requirement for VoIP services and the step DIY deployments most often miss. Test it with the provider's test procedure, not by dialling 999.

Step 8: pilot, port, go live

A single department uses the new set-up for a week with the old system still in place. Fix what they find - usually a voicemail greeting, a caller ID rule or a queue overflow. Then the port completes on the agreed date, the remaining users are switched, and the old lines are ceased. Keep the hosted and Teams sides in one support relationship; a fault that starts with two suppliers blaming each other is the failure mode to design out.

Costs to expect

As an illustrative September 2026 guide, ex VAT: a Teams Phone licence at single-digit pounds per user per month (check current Microsoft pricing); a route at roughly £9 to £11 per user for a Microsoft domestic Calling Plan or roughly £3 to £8 per user for UK minutes through Operator Connect or Direct Routing, the latter plus an SBC; hosted seats for reception and call-heavy teams at roughly £8 to £20 per user; certified desk phones at £120 to £300 if wanted. The comparison against a pure hosted system is in what hosted telephony costs.

Common mistakes

• Putting reception on Teams and discovering the console problem on day one.
• Porting numbers before the queues and attendants are built.
• Forgetting caller ID rules, so staff show personal DDIs on outbound calls.
• Skipping 999 location configuration.
• Assuming existing SIP desk phones will work with Teams.
• Two suppliers for one phone system, with a gap between them.

The bottom line

Integrating a phone system with Teams is a well-trodden project when the design is right: Teams Phone via Operator Connect for the office, a hosted platform for reception and call-heavy teams, numbers ported after the build is tested, 999 configured before anyone goes live. Done in that order it takes a few weeks and removes a supplier; done in the wrong order it produces the horror stories.

We design and build these integrations, both sides, under one support relationship: get a no-obligation quote or call 0333 006 9399. Our hosted telephony service page explains how a quote works.

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