What Is Teams Direct Routing? How to Make Calls from Microsoft Teams

If your business already uses Microsoft Teams for chat and video meetings, you might wonder why you still need a separate phone system. The answer is Teams Direct Routing — a feature that turns Microsoft Teams into a full-featured business phone system, letting you make and receive external calls to landlines, mobiles, and international numbers directly from the Teams interface.

In this guide, we explain exactly how Direct Routing works, who it suits, what it costs, and how to get started.

What Is Teams Direct Routing?

Teams Direct Routing is a method of connecting Microsoft Teams to the public telephone network (PSTN) via a third-party SIP trunk provider. Instead of buying Microsoft's own Calling Plans, you route voice traffic through a certified Session Border Controller (SBC) linked to an external carrier.

This means you can:

• Make and receive external phone calls inside Microsoft Teams
• Keep your existing phone numbers and porting arrangements
• Choose a UK-based SIP provider with competitive call rates
• Combine Teams with existing PBX infrastructure during migration
• Scale call capacity without per-user calling add-ons from Microsoft

How Does Teams Direct Routing Work?

The architecture is straightforward. Your Teams environment connects to an SBC — either a physical appliance on your network or a cloud-hosted SBC managed by your provider. The SBC bridges Teams and the SIP trunk, translating protocols so calls flow seamlessly between Teams users and the outside world.

Here is the typical call flow:

1. A Teams user dials an external number from their desktop, mobile, or web client.
2. Teams routes the call to the SBC via Microsoft's cloud infrastructure.
3. The SBC forwards the call over the SIP trunk to the PSTN carrier.
4. The call connects to the recipient's phone — landline, mobile, or international.

Inbound calls follow the reverse path: they arrive on the SIP trunk, pass through the SBC, and ring in the Teams client.

What Do You Need for Direct Routing?

Before enabling Direct Routing, you need a few components in place:

• Microsoft 365 licences — Each user needs a Microsoft 365 plan that includes Teams, plus a Teams Phone Standard licence (formerly Phone System).
• A certified SBC — Either on-premises hardware (e.g., AudioCodes, Ribbon) or a cloud SBC service from your provider.
• SIP trunks — Provided by a UK carrier with PSTN connectivity and number hosting.
• DNS and certificates — Proper TLS certificates and DNS records so the SBC can authenticate with Microsoft 365.
• Admin access — A Teams administrator must configure voice routing policies, dial plans, and PSTN usage records in the Teams admin centre.

Direct Routing vs Microsoft Calling Plans

Microsoft offers its own Calling Plans as an alternative to Direct Routing. Here is how they compare:

• Flexibility: Direct Routing lets you choose any SIP provider and negotiate rates. Calling Plans lock you into Microsoft's pricing and geographic availability.
• Cost at scale: For businesses with more than 20–30 users, Direct Routing is usually cheaper because SIP trunk pricing scales better than per-user Calling Plan licences.
• Number porting: Direct Routing makes it easier to port existing numbers from legacy carriers. Calling Plans require porting numbers into Microsoft, which can be slower.
• Hybrid setups: Direct Routing supports hybrid configurations where some users stay on a legacy PBX while others move to Teams. Calling Plans are Teams-only.
• Call recording and compliance: Third-party SIP providers often include call recording, fraud protection, and compliance features that Calling Plans do not.

Who Should Use Teams Direct Routing?

Direct Routing is the right choice if your business:

• Already uses Microsoft 365 and Teams for collaboration
• Wants to consolidate telephony into a single platform
• Has multiple office sites or remote workers who need consistent call quality
• Needs to retain existing phone numbers during migration
• Wants competitive UK call rates rather than Microsoft's bundled pricing
• Requires advanced call features like call queues, auto attendants, and recording

It is particularly popular with mid-market businesses (50–500 users) that want enterprise-grade telephony without enterprise-grade costs.

How Much Does Teams Direct Routing Cost?

Costs vary depending on your provider, but a typical UK breakdown looks like this:

• Teams Phone Standard licence: Around £6–£8 per user per month (included in some E5 plans).
• SIP trunk charges: £3–£7 per channel per month, depending on the provider and volume.
• SBC costs: A cloud-hosted SBC is often included by managed providers. On-premises SBCs cost £1,000–£5,000 depending on capacity.
• Call charges: UK landline calls from 0.5p per minute; mobiles from 2p per minute. Many providers offer inclusive bundles.

For a 50-user business, Direct Routing typically costs 30–50% less than Microsoft Calling Plans once you factor in call volumes and international usage.

Setting Up Direct Routing: A High-Level Overview

While the technical setup is best handled by a certified provider, here is what the process involves:

1. Audit your current setup — Review existing numbers, call flows, and SIP infrastructure.
2. Choose a SIP trunk provider — Select a UK provider with Microsoft-certified SBC support.
3. Provision the SBC — Deploy and configure the SBC with TLS certificates and SIP trunk credentials.
4. Configure Teams voice policies — Set up dial plans, voice routing policies, and PSTN usage records in the Teams admin centre.
5. Assign licences and numbers — Apply Teams Phone licences and assign DDI numbers to users.
6. Test and migrate — Run pilot calls, validate call quality, and migrate users in phases.

Most managed providers can complete the setup in five to ten business days, including number porting.

Common Questions About Teams Direct Routing

Can I keep my existing phone numbers?
Yes. Your SIP trunk provider handles number porting from your current carrier, and numbers are assigned to Teams users via Direct Routing.

Does it work with Teams on mobile?
Absolutely. Calls route to whichever Teams client is active — desktop, mobile, or web browser.

What happens if my internet goes down?
Most providers offer failover options, such as routing calls to mobile numbers or a secondary site. Survivable Branch Appliances (SBAs) can also provide local PSTN breakout during outages.

For a deeper look at enterprise voice and UCaaS options, see our guide to enterprise VoIP and UCaaS solutions in the UK. You may also find our overview of Microsoft 365 for business helpful when planning your licensing.