Microsoft Teams Direct Routing

Microsoft Teams Direct Routing is a way to connect Teams Phone to the public telephone network using a carrier you choose rather than Microsoft. A session border controller (SBC), a device or virtual appliance that sits between two voice networks, links Microsoft’s cloud to your carrier’s SIP trunks. Once it is in place, Teams users can call and receive calls from ordinary phone numbers, while you keep your existing carrier, rates and numbers.

At a glance

• Direct Routing is one of Microsoft’s options for PSTN calling in Teams, alongside Calling Plans and Operator Connect.
• It needs a Microsoft-certified session border controller, run by you or hosted by a provider, and a SIP trunk from a carrier.
• Users need Teams Phone licensing; calling minutes and numbers come from the carrier.
• It suits companies that want their own carrier, need countries Microsoft doesn’t serve directly, or must keep a PBX or analog devices connected.
• You (or your provider) own more of the setup, including emergency calling configuration, monitoring and SBC upkeep.

What problem it solves

Teams gives people chat, meetings and internal calling. To make Teams a full phone system, users also need to call outside numbers, which means connecting Teams to the public switched telephone network (PSTN). Microsoft’s own Calling Plans are the simplest route, but they are available only in certain countries, come at Microsoft’s rates and require moving numbers to Microsoft.

Direct Routing lets a company bring its own carrier. That matters when you have negotiated rates, operate in countries Calling Plans doesn’t cover, want one carrier across Teams and other systems, or need to keep an existing PBX, contact center, paging system or analog devices working alongside Teams during a gradual migration.

How it works

1. The SBC. A session border controller from Microsoft’s list of devices certified for Direct Routing is deployed on site, in a data center or as a virtual machine in a public cloud, or is provided as a managed service by a carrier or partner. It connects to Microsoft’s cloud over the internet using encrypted signaling and media.
2. The carrier connection. On the other side, the SBC connects to one or more SIP trunks from your carrier, and optionally to existing PBXs or analog gateways.
3. Teams configuration. In Teams, administrators register the SBC, assign phone numbers to users, call queues and auto attendants, and create voice routing policies that decide which SBC and trunk each call uses.
4. Media path. By default, call audio flows through Microsoft’s cloud. Features such as media bypass and local media optimization can keep audio closer to users when configured; whether they help depends on your network.

Resilience. Redundancy comes from deploying SBCs in more than one location, using more than one trunk or carrier, and configuring failover routes. Microsoft also supports survivable branch options for sites that may lose their internet connection, depending on the SBC.

Emergency calling. Teams can pass the caller’s location with emergency calls, but over Direct Routing that depends on network location settings in Teams, the SBC and the carrier or emergency routing service. See E911 for how location-based emergency calling works; requirements differ by country and, in the US, by state.

When it matters for buyers

• When moving phone service to Teams and deciding between Calling Plans, Operator Connect and Direct Routing.
• When operating in several countries, especially where Calling Plans or a preferred carrier’s Operator Connect service is not available.
• When keeping legacy systems, such as a PBX, contact center, fax or door phones, connected during or after the move.
• When renewing carrier contracts, since Direct Routing makes the carrier a separate, competitive choice.
• When you lack in-house voice expertise. A managed Direct Routing service shifts SBC operation to a provider but adds a monthly fee.

Questions to ask vendors

• Is your SBC (or the one you recommend) certified by Microsoft for Direct Routing, and who maintains it?
• Do you offer Direct Routing as a managed service, Operator Connect, or both, and which fits our countries?
• How are SBCs and trunks made redundant, and what happens to calls if one fails?
• How do you handle emergency calling, including location for remote and mobile users?
• Can you port our existing numbers, and how long will it take for each country?
• What are the rates for domestic, international, toll-free and mobile calls, and what fees and taxes apply?
• How do you monitor call quality and alert us to problems?
• Can you connect our existing PBX, contact center or analog devices during migration?

How it differs from Operator Connect and Calling Plans

All three put PSTN calling into Teams Phone. Calling Plans make Microsoft the carrier, with the least setup but limited country coverage and less pricing flexibility. Operator Connect lets a participating carrier provide service through a direct connection to Microsoft, with numbers assigned in the Teams admin center and no SBC for you to run. Direct Routing offers the most choice and control, including a choice of compatible carriers and connections to other voice systems, in exchange for owning or contracting the SBC and its configuration. Coverage for each option changes over time, so check current availability for your countries.

For buying guidance, see our Microsoft Teams PSTN connectivity solution page.

Problems this helps with

• Using Teams as our phone system without changing carriers
• Microsoft Calling Plans aren't available in some of our countries
• Keeping an existing PBX or analog devices while moving users to Teams
• Calling costs that are higher than our negotiated carrier rates