How SBCs Work for Microsoft Teams Direct Routing

Session border controllers play a crucial role in Direct Routing, Microsoft Teams' SIP trunking feature. While SBCs are not a new technology, their recent popularity is thanks to Teams. But what does an SBC do in Teams and do you need one? We break down what you need to know here. 

sbc microsoft teams

Session border controller (SBC) is a term many businesses are hearing for the first time. Although SBCs are not a new concept, they play a crucial team in SIP trunking and more specifically, Direct Routing for Microsoft Teams. Companies migrating to the cloud with a system like Teams quickly discover that it pays to have options when it comes to the voice solutions they connect to Teams, and an SBC is what gives you options within Microsoft's phone system. With an SBC, you can power your Teams phone system with practically any voice service of your choice.

If you’ve looked up SBCs and you’re not already a seasoned Sys Admin, you’ve seen the technical definition we’re all familiar with. It goes something like this: 

A session border controller (SBC) is a device frequently used in VoIP networks to exert control over the signaling and media streams involved in setting up, conducting, and disconnecting telephone calls and other communication channels.

But what does that mean in plain english? Think of SBCs as a special device that allows you to connect different voice services to your phone system, a process known as SIP Trunking. Setting up an SBC solution for SIP Trunking (known as Direct Routing in Microsoft Teams) is a critical step in unifying your communication channels in the cloud, especially when using a phone system like Microsoft Teams. 

Related reading: What is a Session Border Controller (SBC)?

How SBCs Improve SIP Trunking

SBCs secure your network and unify your communication channels. They also allow you to set up a SIP trunk with a system like Microsoft Teams. The roles that and SBC plays in SIP trunking include: 

  • Security. SBCs protects against cybersecurity threats with methods like Denial of Service (DoS) Prevention, topology hiding, signaling & media encryption and more.
  • Quality of Service. QoS monitoring means setting minimum standards for carrier route quality before connecting callers to prevent poor audio quality, lags in service, and dropped calls. 
  • Unified Communications. Your SBC is responsible for normalizing SIP codecs, local policy controls, security standards, and much more between different carriers within your unified communication platform. 
  • Reduced Cost of Ownership. SIP trunking allows you to connect voice services with better quality at lower rates than standard Calling Plans in Teams. In addition, SBCs also drive your savings up via Least Cost Routing (LCR). 

The Role of a Session Border Controller in Teams

Why should you consider getting an SBC to use with Teams? Plain and simple, Microsoft requires you to use an SBC to set up SIP Trunking in Teams, which they call Direct Routing. With Direct Routing, you are no longer bound to limitations of Microsoft's default Calling Plans. 

SBCs & Direct Routing in Teams

Here is a simple way to think about it. Every phone system needs a phone service powering it, and the phone service has to connect to that system somehow. A SIP trunk is that connection, and an SBC is what you use to create that SIP connection in Teams. So if Teams is your phone system, but instead of relying solely on a Calling Plan as your phone service, you can use Direct Routing (SIP trunking) to connect a different carrier. An SBC is a required tool for direct routing in Teams. 

microsoft teams direct routing diagram

Why So Many Teams Choose Direct Routing

While a Teams Calling Plan works fine for many small businesses, they are a poor fit in many scenarios. When should you consider setting up SBC solutions for Direct Routing? When we help companies set up Direct Routing, the most common reasons we hear for expanding past Calling Plans include:

  • International Numbers. Companies with international presence will use SIP trunking to connect phone numbers that Microsoft can't provide into their Teams phone system. Microsoft currently only offers select number types in 16 countries. For comparison, a direct routing soltution with AVOXI includes number availability in 170+ countries.
  • Reduced Cost of Ownership. Like we said before, Calling Plans work fine for some small businesses. But if your Team makes more than a few calls per day, or if you regularly make or receive international calls, Direct Routing allows you to connect a voice service built for your needs and take advantage of superior call rates than offered in Calling Plans.
  • Call Quality. And SBC optimizes your SIP trunk (Direct Routing) connections so that your voice traffic is always carried through the path of least resistance within your telecom networks. This means consistent, high-quality calling for a golden customer experience.
  • International Caller ID. Companies dialing calls internationally often notice issues with their outgoing caller ID. This is due to complications at the carrier level. With Direct Routing, you can connect their Teams phone system with a service like TrueLocal®, ensuring your caller ID preferences when dialing international numbers.

Related reading: Direct Routing vs. Calling Plans in Microsoft Teams

Common Questions About SBCs for Direct Routing

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  • Certified SBC solution. AVOXI offers hosted SBC solutions, allowing direct routing customers to choose a component-based or fully-managed service.
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