Teams Direct Routing in Luxembourg: A Practical Guide for IT Managers
by PBX.lu Editorial on July 7, 2026
⏱ 13 min read · Article · Microsoft Teams
This guide is for IT managers planning or evaluating a Direct Routing deployment. You already run Microsoft Teams. Your users chat, meet, and share files in it every day. The open question is whether Teams should also carry your external phone calls, and if so, how to connect it to the public phone network without breaking calling for the business. Direct Routing is one way to make that connection. This guide is written for the person who has to plan it, budget it, and own it when something goes wrong: the IT manager.
This is a decision and planning guide, not a wiring diagram. If you want the step-by-step mechanics of how a call travels from Teams to the phone network, read the companion explainer, How Direct Routing works in Microsoft Teams. Here the focus is on trade-offs, hidden work, a worked example, timeline, and who is accountable when a call fails.
🧭 Key takeaway. Direct Routing is rarely the hardest technical choice; it is an ownership choice. It gives you the most control over operator, routing, and numbers, in exchange for more moving parts and a split chain of responsibility. For many 50-person companies, the real question is not "can we do Direct Routing" but "do we want to run it ourselves, hand the hard part to an operator, or avoid it with a simpler model."
The decision you are actually making
An IT manager almost never chooses Direct Routing in isolation. You are choosing how to give Teams a dial tone, and Direct Routing is one of four common paths. Getting the frame right prevents most later regret.
Teams Phone. The Microsoft add-on licence that lets a Teams user make and receive calls to ordinary phone numbers. Without it, Teams handles only internal calls and meetings.
Direct Routing. A supported way to connect Teams to any telephone operator through a certified device called a Session Border Controller.
Operator Connect. A lighter model where an approved operator links its network to your Teams tenant for you. There is no device for you to run.
Calling Plan. Microsoft sells you the numbers and minutes directly. It is available only in some countries, and coverage in the Greater Region is uneven.
📦 Calling Plans
You run nothing extra; Microsoft supplies the numbers and minutes.
Best fit: small teams in countries Microsoft covers, with simple needs.
🔗 Operator Connect
You run nothing; an approved operator links its network to your tenant for you.
Best fit: you want Teams calling with little admin and a local operator is on the list.
⚙️ Direct Routing
You run a certified SBC, self-managed or operator-hosted, plus a SIP trunk.
Best fit: you need a specific operator, custom routing, or an operator not on Operator Connect.
🏢 Cloud PBX with Teams integration
You run a hosted phone system that connects to Teams.
Best fit: you want advanced call features, or to keep a system that already works.
The trap is treating this as purely technical. It is mostly about who carries the operational load, and where accountability sits when a number stops ringing.
Direct Routing or a Cloud PBX under Teams
A common misread is that Teams must replace your phone system. It does not have to. Many businesses keep a Cloud PBX as the calling engine and connect Teams to it, so users can dial from Teams while the PBX handles queues, recording, and reporting.
Cloud PBX. A phone system delivered as an online service, with call routing, voicemail, menus, and reporting managed in a web portal rather than on a box in your server room.
The provider landscape in Luxembourg and the Greater Region splits roughly in two, and the difference matters for accountability. Infrastructure operators own national fibre and their own data centres, so more of the chain sits under one roof. Full-stack service providers deliver voice and Cloud PBX by layering over one or more backbone partners rather than owning a national fibre backbone and their own data centres. Both can deliver Direct Routing or a hosted SBC well. What changes is how many companies are in the room when you need a fault fixed fast.
🔁 Self-managed SBC or operator-hosted: how to choose
Running your own SBC gives you full control and can lower per-minute cost at scale, but you own the firmware updates, the certification, the security hardening, and the 3am call when it stops. An operator-hosted SBC folds all of that into a service and an SLA, which suits most companies under a few hundred users. As a rule of thumb: choose self-managed only if you have in-house SIP expertise and a reason the hosted option cannot meet. Otherwise, hosted is the lower-risk default.
A worked example: a 50-person company
Picture a services company with 50 staff in one Luxembourg office. About 15 work cross-border or from home in France, Belgium, and Germany. Everyone already has Microsoft 365 and lives in Teams. The old on-premises phone system is tied to an ageing SIP trunk, the contract is ending, and the business wants everyone calling from Teams on their existing numbers.
Direct Routing can absolutely serve this company. The honest picture has two sides.
✅ Where Direct Routing fits them well. They keep their current Luxembourg numbers and can pick any operator, including one that already serves the Greater Region. There is one consistent calling experience in Teams for office and remote staff. Routing rules can give the sales team open international calling while limiting other groups. With an operator-hosted SBC, there is no hardware in the office.
⛔ Where it costs them more than expected. Every calling user needs a paid Teams Phone add-on on top of Microsoft 365. Emergency calling for staff in four countries must be designed and tested, not assumed. When a call quality issue appears, the fault could sit with Microsoft, the SBC, the operator, or the local network, and someone has to coordinate all four.
⚠️ Where it depends. If a local operator this company likes is already on Operator Connect, that simpler model may reach the same result with less to run. Direct Routing earns its extra complexity when they need a specific operator, unusual routing, or features Operator Connect cannot give.
For this company, the sensible default is Direct Routing with an operator-hosted SBC, or Operator Connect if their preferred operator is listed. Self-managing an SBC for 50 users rarely pays off.
The challenges IT managers underestimate
The mechanics of Direct Routing are well documented. The operational realities are where projects slip. These are the ones that catch teams out.
Session Border Controller (SBC). The certified device, physical or virtual, that sits between Teams and the operator. It is the single point every external call passes through, so it is both the workhorse and the risk.
The split-responsibility problem. This is the single biggest change for an IT manager. With a traditional phone line, one company owns the fault. With Direct Routing, a single failed call can touch Microsoft, the SBC provider, the operator, and your own network. Nobody owns the whole chain by default. You do, unless your contract says otherwise.
🧭 Who to call when a call fails
Map ownership before go-live, not during an outage. Write down, for each layer, who is responsible and how you reach them: Microsoft for the tenant and licensing, the SBC provider or your own team for the device and its config, the operator for the trunk and the public network, and your network team for internet, firewall, and Wi-Fi. If one company hosts the SBC and provides the trunk, your chain is shorter and your outage calls are simpler. That consolidation is often worth more than a lower per-minute rate.
Emergency calling is compliance, not a setting. A user might dial 112 from the Luxembourg office one day and a German home the next. The call must reach the right emergency centre with the right location.
⚠️ Emergency calling must be designed and validated per country before go-live. In the EU, 112 calls must route correctly and carry location information. Under Direct Routing this is your responsibility, not Microsoft's. Each country in the Greater Region has its own emergency routing rules, so home and remote workers need special attention.
PSAP. The Public Safety Answering Point, the emergency call centre that must receive a 112 call and the caller's location. Different countries route to different PSAPs.
Licensing math that grows quietly. Teams Phone is a per-user cost on top of Microsoft 365, and it is easy to underestimate across 50 people, then again as headcount grows. Operator minutes or trunk fees sit on top of that.
Number sync and porting. Every number lives in two places: the operator and the Teams admin centre. If they do not match exactly, inbound calls fail silently. Porting your existing numbers is handled by the operator and needs a planned window.
One SBC is one point of failure. A single SBC means all external calling depends on one device. Microsoft recommends at least two. For an operator-hosted service, confirm redundancy is included and check the failover target in the SLA.
🏠 Why remote and VPN calls sometimes sound worse
Teams can send call audio straight between the user and the operator, skipping the SBC, which improves quality. This works best on wired office networks. Over a home connection or a VPN, that shortcut often cannot apply, so audio takes a longer path and can degrade on a congested link. For a company with cross-border and home workers, test call quality from real remote setups during the pilot, not only from the office.
🧮 A quick way to sketch the monthly cost
Before you ask for quotes, build a rough model so nothing surprises you. Add up: Teams Phone licences per calling user per month, the operator's trunk or channel fee, expected call minutes by destination, any hosted-SBC service fee, and one-off porting and setup costs. Do it once for today's headcount and once for a larger future one. This is a telecom budgeting exercise, and it turns "it depends" into a number you can defend.
A realistic timeline
For 50 users, plan for roughly six to ten weeks from decision to full cutover. Rushing the pilot and the emergency-calling tests is where quality problems slip into production.
- Scope and licences (Week 1). Confirm Teams Phone licences, pick the connection model, and choose your operator or partner.
- Design (Weeks 1 to 2). Agree the number plan, routing policies, emergency addresses, and the redundancy decision.
- Build (Weeks 2 to 4). Set up and certify the SBC, connect the trunk, and assign test numbers.
- Pilot (Weeks 4 to 6). Have five to ten users test inbound, outbound, 112, transfers, and remote call quality.
- Port and cutover (Weeks 6 to 8). Port the main numbers, move users in groups, and keep the old system as fallback.
- Handover (Weeks 8 to 10). Decommission old lines, document routing, and agree support and SLA.
How to decide
Strip it back to what your company actually needs, then match the model to it.
Choose Direct Routing when you need a specific operator, custom routing across countries, or an operator that is not on Operator Connect, and you accept a longer accountability chain.
Consider Operator Connect when your preferred operator is on the list and you want Teams calling with the least to run.
Keep or choose a Cloud PBX with Teams integration when you need advanced call handling, recording, or reporting beyond what Teams Phone offers on its own.
Look at Calling Plans only if Microsoft covers every country you need, which is often not the case in the Greater Region.
📌 Where this leaves most 50-person companies. Direct Routing with an operator-hosted SBC, or Operator Connect if the right operator is listed. Self-managing an SBC rarely pays off at this size. Whichever you pick, decide who owns each layer, budget the Teams Phone licences honestly, and validate 112 for every country your people work in before you cut over.
The technology is proven. The projects that go well are the ones where the IT manager treated ownership, compliance, and the pilot as the real work, and the wiring as the easy part.
📚 Keep exploring the Microsoft Teams cluster on pbx.lu. Read next: How Direct Routing works in Microsoft Teams · What Microsoft Teams means for fixed-line business telephony · What certifications should your Teams partner have. For an overview, see the Microsoft Teams feature page or compare providers active in Luxembourg and the Greater Region.
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