Your SBC for Microsoft Teams Direct Routing: 2024 guide

During your Microsoft Teams migration, consider having external experts manage your SBC to make the process easier. Here's what you need to know.
Microsoft Teams logo and a server in cloud indicating hosted SBC for Microsoft Teams Direct Routing and how it works

There are a few known facts to life—never wake a sleeping baby, look both ways before crossing the street, and always, always outsource whatever’s not absolutely critical to have in-house.

During your Teams Direct Routing migration, letting external experts manage your Session Border Controller (SBC) can make your journey to the cloud easier. (And did we mention less expensive)?

However, there are a few valid reasons why businesses might choose to manage their SBC in-house. In this blog, we’ll talk about everything you need to consider when asking yourself: What to do about my SBC? 

What you need for a Teams Direct Routing migration

Direct Routing all starts with your Microsoft phone system. Once you get the Teams phone system (the PBX add-on license), you can use Microsoft’s Calling Plans, Direct Routing, or Operator Connect.

Microsoft Teams’ native Calling Plans work well for some businesses that need absolute simplicity. But on the other hand, Direct Routing gives businesses more control over their telephony.

If you decide to go with Microsoft Teams Direct Routing, you need a few basic things:

  1. A Microsoft Teams phone system license in Microsoft 365. This is typically included in the E5 package and as an add-on with the E3 package.
  2. A Direct Routing partner that can provide SIP trunks, phone numbers, access to an emergency services network, and messaging capabilities.
  3. A Microsoft-certified E911 provider with Dynamic Location Routing (DLR) capabilities for nomadic workforces within the United States.
  4. A Microsoft-certified session border controller (SBC) to terminate SIP trunks, create interoperability, and act as your voice firewall.

What is a hosted Session Border Controller?

An SBC is the on-premise or cloud system businesses deploy at the border of private and public networks in order to send media and voice between devices.

In Microsoft Teams, an SBC securely transfers data from Microsoft Phone System—a hosted Private Branch Exchange (PBX)—to the PSTN or aggregate of all global telephone networks.

Enterprise Communications Landscape 2024

Hear how 1,000 IT leaders are migrating to Microsoft Teams and configuring their SBCs.

The pros and cons of hosting your Teams SBC

Microsoft Teams Direct Routing enables Teams customers to connect to local PSTN or SIP trunk providers via a certified SBC. Direct Routing offers Teams customers a great deal of flexibility when it comes to their voice infrastructure, enabling customers to adopt a Bring Your Own Carrier (BYOC) approach and facilitate coexistence with legacy voice and UC systems.

There are many hosted SBC options available in the market. But if you’re specifically looking at Microsoft Teams Direct Routing, you can decide to either buy, own and manage your own SBC, or let your carrier connect you to Teams through a hosted option.

When Microsoft first launched Direct Routing, their model was based on companies managing their own SBC and plugging in Teams. Since then, more and more businesses want a hosted SBC instead.

Here are six reasons why a hosted SBC might be the right choice for your organization:

  1. You’re trying to lower costs by moving from a CAPEX investment model towards OPEX investment by reducing the on-prem equipment you need to service and maintain.
  2. It’s faster to deploy a hosted solution, which will help you keep up with migration timelines and evolving communications needs.
  3. It reduces your need for specialized expertise and investments across PowerShell, VoIP engineering, certifications, and anything else required to manage your own SBCs in-house.
  4. It simplifies your infrastructure management globally as managing telephony infrastructure internationally becomes increasingly complex.
  5. It increases security & quality because your SBC acts as a voice-aware firewall and encryption protects your voice traffic, preventing bad actors from entering your data network.
  6. You need interoperability across your communications ecosystem and systems with platform-agnostic SIP and porting tools.

Why you would keep your Microsoft Teams SBC

If you’ve already got a certified SBC, there are many reasons not to outsource the hosting to another provider. These reasons might include:

  • Legacy systems that are analog gateways that you still need to support
  • Using existing contact center or unified communications platforms that require dialing within Microsoft Teams
  • The use of Registering devices
  • Desire to maintain infrastructure in the call flow

Whatever your reason might be, you can always readjust your communications strategy down the line if hosting becomes the right choice.

Your call flows with a hosted SBC in Microsoft Teams

Whether you choose to host your SBC or not, Teams will send voice calls to the SBC, and then to the PSTN or emergency services provider with IP-based SIP trunks.

If you choose Bandwidth to host your SBC, each call will come directly to our Microsoft-certified SBC over our peered links with Teams. In the flow below, the call happens securely with the cross-connect and there’s no public internet piece for this leg of the call:

diagram of how call flows work with microsoft teams direct routing - hosted sbc option

Note: whether you own or host your Microsoft Teams SBC, you’ll be running TLS encryption so that call will be secured by TLS/SRTP. 

Think beyond your Microsoft Teams migration

If you love Microsoft Teams, but decide you want to go somewhere else in the future, or you want to send numbers to another platform, hosting your SBC with a platform-agnostic carrier like Bandwidth means you can manage numbers by simply pressing a button.

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