In short: Teams Direct Routing connects Microsoft Teams Phone to any PSTN carrier or SIP trunk through a Microsoft-certified Session Border Controller (SBC), run by you, an integrator or a Direct Routing as a Service provider. It suits organisations keeping a carrier or numbers, linking an existing PBX or analogue devices, or needing specific routing. Users need Teams Phone.
What Direct Routing is
Direct Routing lets you connect your own telephony to Microsoft Teams Phone using a supported Session Border Controller (SBC). The SBC is the bridge: on one side it talks to Microsoft's Direct Routing service, and on the other it talks to SIP trunks, a PBX, analogue gateways or other devices.
Microsoft's PSTN guidance says the SBC can be procured, installed and managed by you, by an integrator, or by a Direct Routing as a Service (DRaaS) provider. With DRaaS the SBC runs in the provider's cloud, so there is no hardware on your site. Our own Forever Teams service and Call2Teams both work this way.
When Direct Routing suits
Microsoft describes Direct Routing as a good fit for organisations that:
- Have an existing PSTN carrier relationship
- Need to integrate third-party PBXs or analogue devices, such as door entry, lift lines, fax or overhead paging
- Need advanced voice routing capabilities
- Want greater control over their telephony infrastructure
- Run complex or multinational voice deployments
It is also how a UK provider can offer Teams calling with its own numbers, itemised billing and support, as Forever Teams does. Microsoft supports Direct Routing alongside Calling Plans, Operator Connect and Teams Phone Mobile in the same tenant, and gives examples such as Direct Routing for contact centres, analogue devices and legacy PBXs while other users take a different option.
How it works
At a technical level, Microsoft's planning guide sets out these components:
| Component | What it involves |
|---|---|
| Certified SBC | An SBC model Microsoft has certified for Direct Routing. Microsoft only supports Direct Routing with certified SBCs |
| Trunks | One or more SIP trunks or PSTN connections to the SBC (see SIP trunks) |
| Domain and certificate | The SBC's name must sit in a verified Microsoft 365 domain (not onmicrosoft.com), with a public certificate from a trusted authority |
| Secure signalling | SIP over TLS to Microsoft's three Direct Routing connection points, with automatic failover between regions |
| Media | Encrypted media (SRTP) via Microsoft's media processors, or directly between client and SBC with media bypass |
| Codecs | Microsoft lists SILK, G.711, G.722 and G.729 between Teams and the SBC, plus AMR-WB when media bypass is not used |
| Licences and policy | Microsoft Teams and Teams Phone for each user, with an online voice routing policy assigned |
With DRaaS, the provider handles the SBC, certificates, firewall rules and carrier trunks. You assign licences and numbers in Microsoft 365, and the provider configures routing.
Ways to run Direct Routing
| Model | Who runs the SBC | Often suits |
|---|---|---|
| Your own SBC | Your IT team, on site or in your cloud | Large estates with in-house voice skills and specific integration needs |
| Integrator-managed | A specialist that builds and supports the SBC for you | Organisations with an on-site PBX, analogue estate or several countries |
| Direct Routing as a Service | The provider, in its own cloud | Most small and mid-sized organisations: no hardware, a monthly service and one support desk |
Our two DRaaS routes are Forever Teams, Forever Group's own Teams calling service with your numbers and UK call billing, and Call2Teams, which brings an existing PBX or SIP trunk provider into Teams. If you run 3CX, the 3CX Microsoft Teams integration is another way to combine a PBX with Teams.
Things to plan for
Direct Routing gives you control, which also means more decisions:
- Support boundaries. Microsoft supports Direct Routing only with certified SBCs, and faults go first to the SBC vendor or provider, who escalates to Microsoft if needed.
- Resilience. Plan redundant SBCs or trunks and test failover. A DRaaS provider should explain how its platform handles a data centre or carrier outage.
- Emergency calls. Set emergency addresses for each site so 999 calls present the right location.
- Common area phones. Microsoft notes they need no Calling Plan with Direct Routing; they still need a Shared Space licence.
- Auto attendants and queues. Resource accounts with Direct Routing numbers need an online voice routing policy for outbound calls. Microsoft says the November 2025 Calling Plan change for resource accounts does not affect Direct Routing numbers.
- Network. Teams calls need good upload capacity and quality of service on your network. See hosted VoIP.
How we help
We design and run Direct Routing so it feels as simple as a Calling Plan:
- Review your numbers, carriers, PBX and any analogue devices.
- Recommend Forever Teams, Call2Teams, or a mix with Calling Plans or Operator Connect.
- Supply Teams Phone and Microsoft licences, and set up voice routing and emergency addresses.
- Port your numbers with temporary diverts where needed.
- Test inbound, outbound, transfers and failover, then support you afterwards.
Still weighing the options? Read Direct Routing vs Operator Connect vs Calling Plans, or contact us for a recommendation.
Why choose your cloud phone system with Forever Systems
We are vendor-neutral. Forever Group supplies and supports several cloud phone platforms, so we recommend the one that fits how your organisation works rather than the one we happen to sell.
- Side-by-side comparison of hosted 3CX, Microsoft Teams Phone, Forever UC, Forever Teams and Webex Calling for your users
- Contact centre and call recording options matched to your call volumes and CRM
- Number porting, handsets and set-up handled for you, including the move off analogue and ISDN lines
- Connectivity checked so call quality is right from day one
- UK support for moves, adds, changes and faults
- For BT Cloud Voice, see our BT Business Partner site cloudvoice.cloud
We work with businesses, schools, charities and public sector organisations. We do not sell consumer phone services.
Want a vendor-neutral cloud phone system comparison and quote?
Tell Forever Systems what you need and we will come back to you by email with options, not a hard sell.
Contact usFrequently asked questions
What is Direct Routing in Microsoft Teams?
Direct Routing connects Microsoft Teams Phone to any phone carrier, SIP trunk or PBX through a Microsoft-certified Session Border Controller. The SBC can be run by you, an integrator or a Direct Routing as a Service provider.
Do I need my own Session Border Controller for Direct Routing?
No. With Direct Routing as a Service, the provider runs the certified SBC in its own cloud, so there is no hardware on your site. Forever Teams and Call2Teams both work this way.
What licences does Direct Routing need?
Each user needs Microsoft Teams and a Teams Phone licence. You do not need a Microsoft Calling Plan, because calls are carried by your Direct Routing provider or carrier.
Can I use Direct Routing and Calling Plans together?
Yes. Microsoft supports Direct Routing alongside Calling Plans, Operator Connect and Teams Phone Mobile in the same tenant, so different users or sites can use different options.
Can analogue devices work with Teams Direct Routing?
Yes. Analogue devices such as door entry phones or fax machines can connect through an analogue gateway and SBC using Direct Routing. Plan these carefully, especially ahead of the PSTN switch-off.