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In this section:

This article introduces MS Teams Direct Routing and Ribbon SBC Core, and describes the prerequisites for configuration.

About Teams Direct Routing

MS Teams Direct Routing allows connecting SBC Core, or a customer-provided SBC, to a Microsoft Phone System. You can connect the SBC to almost any telephony trunk, or connect it with third-party PSTN equipment.

About Ribbon SBC Core

Ribbon's Session Border Controllers (SBCs) provide robust security, simplified interoperability, advanced session management, and carrier-grade reliability for enterprises and service providers.  Ribbon's SBCs offer powerful deployment flexibility that meets or exceeds the demanding levels of security and service quality for applications such as SIP trunking, Unified Communications, Network-Network Interconnection, VoLTE, VoWiFi, and RCS.

The Ribbon SBC Core supports MS Teams on the SBC 5110/5210/5400, SBC 7000, as well as the SBC SWe on KVM, VMware, Xen hypervisors or a private/public cloud.

Validated Ribbon SBC Version

Microsoft successfully conducted validation tests with Ribbon SBC Core versions V6.2 and V7.2.  Other firmware versions may run successfully; however, Microsoft did not test such versions. For an updated list, refer to the page on Microsoft's website - https://docs.microsoft.com/en-us/microsoftteams/direct-routing-border-controllers.

Network Architecture

Ribbon SBC Prerequisites

Before starting configuration, ensure that the following prerequisites are fulfilled:

  • To enable direct routing, a Microsoft Phone System license is installed in MS Teams. For more information on Microsoft's licensing requirements, refer to https://docs.microsoft.com/en-us/microsoftteams/direct-routing-plan#licensing-and-other-requirements.
  • Signaling Encryption and Media Encryption licenses are installed on the SBC.
  • For multi-tenant MS Teams deployment, Advance ERE or PSX Access licenses are installed on the SBC. Basic ERE is sufficient for single-tenant MS Teams deployment.

SBC Licensing for MS Teams

Reference Configuration

The following illustration describes the network architecture used for this guide.

SBC - MS Teams - Carrier Trunk and CAC

The SBC performs a failover to another Office 365 site when the primary data center site is down. Currently, Microsoft Office 365 uses the following sites.

  • sip.pstnhub.microsoft.com
  • sip2.pstnhub.microsoft.com
  • sip3.pstnhub.microsoft.com

The following figure illustrates the configuration.

Site Failover Architecture

Equipment and Software

The configuration examples in this solution guide use the following equipment, elements, and software:




Software Version

Ribbon Elements 

Ribbon SBC 5400
ConnexIP OS


Third-party Equipment

Microsoft Teams

v.2018.7.3.2 i.ASEA.3

Teams Client1.1.00.28562 

Administration and Debugging Tools



Infrastructure Prerequisites

For information on infrastructure prerequisites, refer to the section "Infrastructure requirements" of Microsoft's document https://docs.microsoft.com/en-us/microsoftteams/direct-routing-plan.

As a quick reference, the above article includes the following topics:

  • Session Border Controller (SBC)
  • Telephony trunks connected to the SBC
  • Office 365 tenant
  • User registrar
  • Domains
  • Public IP address for the SBC
  • Fully Qualified Domain Name (FQDN) for the SBC
  • Public DNS entry for the SBC
  • Public trusted certificate for the SBC
  • Connection points for Direct Routing
  • Firewall IP addresses and ports for Direct Routing media
  • Media Transport Profile
  • Firewall IP addresses and ports for Microsoft Teams media


  • Microsoft – For a list of Ribbon SBC products supported for MS Teams, refer to the following page on Microsoft's website - https://docs.microsoft.com/en-us/microsoftteams/direct-routing-border-controllers.
  • Ribbon – For more information, refer to the following page on Ribbon's website - https://ribboncommunications.com/solutions/enterprise-solutions/microsoft-solutions.

MS Teams Deployment Overview

The following table describes the available routing options, based on the SBC with MS Teams deployment scenario:

Deployment Scenarion and Routing Options

Deployment ScenarioRouting Options
Single-tenant deployments
  • Basic ERE
  • Advanced ERE (A-ERE)
  • PSX
Multi-tenant deployments
  • Advanced ERE (A-ERE)
  • PSX


Ribbon recommends using Basic ERE only for single-tenant deployments, and A-ERE or PSX for scalable multi-tenant MS Teams configuration.


 To handle traffic for all MS Teams tenants configured on the SBC, this configuration uses a single IP Trunk Group, referred to as a Carrier Trunk, between MS Teams and the SBC.

To enforce CAC on a per-tenant basis, configure dummy trunk groups for each tenant.

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