Posted in MS Teams

Teams Direct Routing

   September 15, 2024

Microsoft Teams Direct Routing: Overview

Microsoft Teams Direct Routing is a feature that allows organizations to connect their on-premises telephony infrastructure (such as PBX systems or existing phone lines) to Microsoft Teams via a Session Border Controller (SBC). This enables users to make and receive external phone calls (PSTN – Public Switched Telephone Network) through Microsoft Teams without needing Microsoft’s Calling Plans. Essentially, Direct Routing allows Microsoft Teams to function as a full-fledged phone system (PBX), leveraging existing phone service providers and infrastructure.

Direct Routing provides flexibility for organizations that:

  • Want to integrate Teams with their existing telephony provider.
  • Operate in regions where Microsoft Calling Plans are unavailable or impractical.
  • Have complex telephony needs (e.g., hybrid telephony environments, legacy systems).

Key Components of Microsoft Teams Direct Routing

  1. Session Border Controller (SBC)
    • Function: The SBC is a critical component of Direct Routing, serving as the intermediary between Microsoft Teams (in the cloud) and the on-premises telephony system. It manages call flows, handles protocol translations, and secures the connection between Teams and the PSTN.
    • Types: SBCs can be either physical devices or virtual software-based systems. They are typically provided by third-party vendors and certified by Microsoft for use with Teams.
    • SBC Capabilities:
      • Routing calls between Microsoft Teams and the PSTN.
      • Translating signaling between different protocols (SIP to Teams protocol).
      • Securing communication by encrypting signaling and media.
      • Enforcing policies such as call routing rules and bandwidth management.
  2. On-Premises Telephony System (PBX or PSTN Provider)
    • Function: This component represents the organization’s existing phone infrastructure, which can include a traditional PBX, ISDN, or SIP trunking provider. Direct Routing allows Teams to route calls through this system to the PSTN.
    • Role: By using Direct Routing, the existing telephony infrastructure continues to handle external calls, but the Teams platform provides the interface for users to make and receive those calls.
  3. Microsoft Phone System
    • Function: The Microsoft Phone System is a cloud-based PBX solution that provides call control and PBX capabilities to Teams users. Direct Routing integrates with the Microsoft Phone System to extend its functionality to external phone systems.
    • Capabilities:
      • Handling call management features like voicemail, call forwarding, call queues, and auto attendants.
      • Integrating with the SBC to route calls between Teams users and the PSTN.
      • Enabling features like call transfer, hold, conference calling, and voicemail transcription.
  4. Microsoft Teams Clients (Users)
    • Function: Users of Microsoft Teams clients (desktop, web, or mobile) can place and receive phone calls using the same interface they use for internal Teams communication. Calls are routed through the Phone System, SBC, and PSTN.
    • Capabilities:
      • Making and receiving external phone calls from the Teams app.
      • Using advanced call features like call transfer, call queues, voicemail, and shared lines.
  5. Public Switched Telephone Network (PSTN)
    • Function: The PSTN is the traditional phone network that allows users to connect with landline and mobile phone numbers. Direct Routing connects Teams users to the PSTN via the organization’s telephony provider, enabling external calling capabilities.

How Direct Routing Works

When a Teams user makes a call to an external phone number:

  1. The call request is initiated from the Teams client.
  2. The Microsoft Phone System routes the call to the SBC.
  3. The SBC translates and routes the call to the on-premises PBX or SIP trunk provider.
  4. The call is connected to the external phone number via the PSTN.

Conversely, when an external call comes into the organization’s PSTN, the reverse flow happens:

  1. The PSTN sends the call to the on-premises PBX or SIP trunk.
  2. The SBC routes the call to the Microsoft Phone System.
  3. The Microsoft Phone System connects the call to the appropriate Teams user.

Key Features of Microsoft Teams Direct Routing

  1. Call Routing Flexibility
    • Direct Routing provides organizations with control over how calls are routed. You can define custom rules for routing calls to specific users, departments, or external numbers based on call type, time of day, or other criteria.
  2. Hybrid Telephony Setup
    • Organizations can operate a hybrid setup where some users are on Teams Calling Plans while others use Direct Routing through their existing telephony provider. This is ideal for phased migrations or organizations with different telephony requirements across regions.
  3. Global Coverage
    • Direct Routing supports global telephony needs by integrating with local or international telephony providers. This is especially useful in regions where Microsoft Calling Plans are unavailable or cost-prohibitive.
  4. Survivable Branch Appliance (SBA)
    • SBA is a device or service deployed on-premises that ensures phone service continuity for Teams users in the event of an internet or Microsoft 365 outage. If Teams is temporarily unavailable, the SBA allows users to continue making and receiving calls via the PSTN.
  5. Call Analytics and Reporting
    • Administrators can track call quality, monitor usage, and analyze call traffic through the Microsoft Teams Admin Center. This ensures a better understanding of call patterns and allows proactive management of the telephony infrastructure.
  6. Security and Compliance
    • The SBC ensures secure communication by encrypting signaling and media streams between Microsoft Teams and the PSTN. Direct Routing also supports call recording, compliance requirements, and call monitoring for industries with strict regulations, such as finance and healthcare.

Step-by-Step: How to Create and Manage Direct Routing in Microsoft Teams

Setting up Direct Routing involves multiple components, including configuring the SBC, setting up the Microsoft Phone System, and connecting everything to the PSTN. Below is a detailed guide on how to set up Direct Routing.

Step 1: Ensure Prerequisites

Before setting up Direct Routing, ensure you have the following:

  • Microsoft 365 Licenses: Ensure that users have the necessary licenses, such as Microsoft Phone System and Microsoft Teams licenses. Without the Phone System license, users cannot utilize Direct Routing.
  • Session Border Controller (SBC): Choose an SBC from the list of Microsoft-certified SBC vendors (e.g., AudioCodes, Ribbon, Cisco). You can deploy the SBC on-premises or in the cloud.
  • Telephony Provider (SIP Trunk/PBX): Ensure you have an existing PSTN service or telephony provider that the SBC can connect to.

Step 2: Configure the Session Border Controller (SBC)

  1. Deploy the SBC:
    • Depending on your infrastructure, deploy the SBC either on-premises or in the cloud.
    • The SBC must be capable of connecting to the PSTN on one side and to the Microsoft Phone System on the other side (via SIP).
  2. Configure the SBC:
    • Use the vendor’s instructions to configure the SBC to communicate with Microsoft Teams. Ensure that the SIP signaling, media encryption, and codec settings align with Microsoft’s requirements.
    • Set up the SIP trunk connection between your telephony provider (or PBX) and the SBC.
  3. Configure Security:
    • Set up TLS certificates for secure communication between the SBC and Microsoft Teams. This includes obtaining and installing certificates from a trusted Certificate Authority (CA).
    • Ensure firewall rules are configured to allow traffic between the SBC and Microsoft 365 services.
  4. Define Call Routing Rules:
    • Configure call routing policies on the SBC to define how calls are routed between Teams users and the PSTN. For example, you can set rules for inbound and outbound calls based on caller ID, destination, or time of day.

Step 3: Configure Microsoft Phone System for Direct Routing

  1. Register the SBC with Microsoft 365:
    • Log into the Microsoft Teams Admin Center and navigate to Voice > Direct Routing.Add your SBC’s FQDN (Fully Qualified Domain Name) and register the SBC in your tenant. You may need to run PowerShell commands to set up the SBC as a trusted device.
  2. Configure Voice Routing Policies:
  3. Define voice routing policies in the Teams Admin Center to determine how calls are routed between Teams and the SBC.
  4. Create and assign voice routes that define which PSTN or SIP trunk to use for specific call types (e.g., local calls, international calls).
  5. Assign Policies to Users:
  6. Assign the Phone System and Direct Routing policies to individual users or groups. This ensures that Teams users are routed through the SBC when they make or receive external calls.

Step 4: Test the Configuration

  1. Place Test Calls:
    • Test inbound and outbound calls to ensure that calls from Teams users are being routed correctly through the SBC and PSTN.
  2. Monitor Call Quality:
    • Use the Call Quality Dashboard in the Teams Admin Center to monitor call quality and identify any issues related to media or signaling.

Step 5: Manage and Maintain Direct Routing

  1. Call Analytics:
    • Use the analytics and reporting tools available in Microsoft Teams to monitor call quality, dropped calls, and call traffic through the SBC.
  2. Adjust Call Routing:
    • As needed, modify call routing policies or SBC configurations to optimize performance, manage call volumes, or troubleshoot issues.
  3. Update SBC Configuration:
    • Keep the SBC’s firmware and software up-to-date to ensure compatibility with Microsoft Teams and to maintain security.

Working and Usage Examples of Direct Routing

1. Global Enterprise with Multiple PSTN Providers

  • A global enterprise with offices in the U.S., Europe, and Asia uses Direct Routing to connect Teams to different local PSTN providers in each region. This setup allows the company to route calls through local phone providers, reducing international calling costs and ensuring compliance with regional telecom regulations.

2. Hybrid Telephony Environment

  • A company with an on-premises PBX system integrates it with Teams using Direct Routing. Some employees continue to use traditional desk phones connected to the PBX, while others use the Teams app on their mobile devices for calling. This allows for a phased migration to Teams without disrupting business operations.

3. Call Center with Advanced Routing Requirements

  • A customer support center uses Direct Routing to connect Teams to their existing call center infrastructure. The SBC is configured to handle complex call routing rules, such as directing calls to agents based on skill level and availability. Teams users in the call center can receive and make calls via the PSTN while using Teams’ chat and collaboration features.

Microsoft Teams Direct Routing provides a flexible and powerful way for organizations to integrate their existing telephony infrastructure with Microsoft Teams. By using an SBC, companies can route calls between Teams and their traditional phone system (PSTN), allowing Teams to serve as the primary communication tool while maintaining control over their telephony services.

Direct Routing is ideal for organizations that need global PSTN connectivity, have complex telephony requirements, or wish to leverage their existing telecom contracts. With the ability to configure call routing, integrate with legacy systems, and provide secure, compliant communications, Direct Routing offers a robust solution for modernizing telephony while maximizing the value of Microsoft Teams.

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Author: tonyhughes