Direct Routing is a feature in Microsoft Teams that allows organizations to use their own Session Border Controllers (SBCs) to connect Microsoft Teams to their existing phone systems, such as a Public Switched Telephone Network (PSTN) or a Voice over IP (VoIP) service provider. This enables organizations to make and receive external phone calls from within the Microsoft Teams application.

Here’s how Direct Routing with Microsoft Teams works:

Microsoft Teams Setup: First, you need to have Microsoft Teams set up within your organization. This involves creating user accounts, setting up Teams channels, and ensuring that your organization is licensed appropriately for calling features.

Session Border Controller (SBC) Configuration: You need to deploy one or more Session Border Controllers (SBCs) within your network or in a data center. The SBC is a key component that connects your on-premises phone system or VoIP provider with Microsoft Teams. The SBC is responsible for routing voice traffic securely between your phone system and Teams.

Configuration in Microsoft 365: Within the Microsoft 365 admin center, you configure the Direct Routing settings. This involves defining voice routes, policies, and connections to your SBCs. You also set up voice routing policies that determine how calls are routed based on factors like user location, phone number, or time of day.

Phone Number Assignment: Assign phone numbers to Microsoft Teams users. These can be Direct Routing numbers that are associated with your existing phone system or numbers provided by your VoIP service provider. Users can also have phone numbers ported into Teams if necessary.

Call Routing: When a user initiates an outbound call or receives an inbound call, the call is routed through the SBCs and then to the appropriate destination based on your configured voice routing policies. The SBCs handle the translation between Teams’ signaling protocols and your existing phone system’s protocols.

Call Quality and Security: Direct Routing includes features for monitoring and ensuring call quality. Microsoft Teams uses the Real-time Transport Protocol (RTP) for media transport, and Secure Real-time Transport Protocol (SRTP) for secure media transmission. Quality of Service (QoS) can be implemented to prioritize voice traffic over the network.

Integration with Teams Features: Direct Routing integrates with other Microsoft Teams features like voicemail, call forwarding, and call queues. This allows for a seamless user experience with all calling and collaboration features available in Teams.

Administration and Monitoring: As an administrator, you can manage and monitor your Direct Routing setup through the Microsoft 365 admin center. You can view call logs, monitor call quality, and make adjustments to routing policies as needed.

By implementing Direct Routing with Microsoft Teams, organizations can leverage the full range of collaboration and communication features offered by Teams while still using their existing phone systems or VoIP providers for external calling. This provides flexibility and allows organizations to gradually transition to a unified communication solution without disrupting their current telephony infrastructure.