Summary: This checklist explains the core technical design elements of Teams Direct Routing and why each one has long-term operational impact. At scale, these decisions stop being architectural preferences and become daily realities that affect call quality, incident response, compliance, and cost.
The shift to cloud collaboration reduced friction in meetings and messaging, but enterprise voice did not simplify in the same way. Voice systems stayed complex because call delivery still has to work under failure conditions and within regulatory constraints.
Teams Direct Routing sits at the center of that complexity. It moves responsibility for carrier selection, call routing, SBC placement, and security decisions out of Microsoft’s managed service and into the enterprise environment. Those choices directly affect how Teams voice behaves when usage increases, how issues are resolved, and how difficult change becomes later.
This checklist is designed to make those decisions visible. It helps IT and voice teams evaluate the technical and operational choices behind their Teams Direct Routing deployment, identify where risk is already embedded, and understand which design elements will matter most as scale, regulation, and complexity increase.
✅ Checklist item: Confirm where SBCs and carrier interconnects are placed.
This is the foundation of any Teams Direct Routing design. SBC location determines media paths, latency, failure domains, and how outages propagate.
If these signals appear, the Teams Direct Routing architecture is likely over-centralized.
✅ Checklist item: Confirm who owns SBC operations and accountability.
SBC ownership defines where responsibility sits during normal operations and during failure. This is often underestimated during Teams Direct Routing design.
✅ Checklist item: Confirm carrier dependency and failover capability.
Carrier strategy is where Teams Direct Routing design meets resilience. It determines whether outages are survivable or service-ending.
Teams Direct Routing supports both models. It does not protect enterprises from the consequences of choosing simplicity over resilience.
If carrier failure equals service outage, resilience is insufficient.
✅ Checklist item: Validate how security and compliance are enforced by design.
Voice introduces a distinct threat surface, and Teams Direct Routing design choices directly affect how exposed the environment is to fraud, toll abuse, and denial-of-service attacks.
SBC placement determines which systems are exposed to the public network, while media flow design controls where call data is processed and stored. Poorly designed environments depend on exceptions and workarounds, whereas well-designed Teams Direct Routing deployments enforce security controls through standard call flows.
Compliance requirements further increase complexity because call recording, monitoring, lawful intercept, and data sovereignty obligations vary by country and by industry. Teams Direct Routing either supports these requirements through its architecture or makes compliance difficult to enforce consistently.
Audits and real-world incidents tend to surface these design weaknesses quickly, often after the environment is already in production.
Be clear on Microsoft responsibility boundaries:
→ Microsoft does not manage carrier interconnects.
→ Microsoft does not troubleshoot SBC-level media failures.
→ Microsoft does not enforce regional compliance.
→ Microsoft does not design carrier failover.
Teams Direct Routing succeeds or fails in the space between Teams and the PSTN.
What good looks like:
✅ Checklist item: Test whether the design can absorb change without re-architecture.
Most Teams Direct Routing environments are designed for stability. Enterprises rarely experience it as change is constant. Mergers introduce new carriers and numbering plans. Expansion pushes Teams into countries without native Microsoft calling options. Compliance requirements evolve. Microsoft certification models change.
Designs that tightly couple Teams, SBCs, and carriers accumulate technical debt. Designs that separate concerns absorb disruption.
Use the questions below to assess operational risk in a Teams Direct Routing environment. Each question highlights a design decision that often looks acceptable during deployment but becomes critical during incidents or periods of change.
Can a single carrier outage impact all users?
If one carrier failure can disrupt service across regions, the design has a large impact range. Teams Direct Routing should limit the scope of carrier failures wherever possible. Outages should remain regional, not enterprise-wide.
Can routing logic change without SBC redeployment?
Routing changes are inevitable. If even minor adjustments require SBC rebuilds or service disruption, operational agility is limited. Well-designed Teams Direct Routing environments allow routing updates without re-architecting the platform.
Is recovery dependent on one team or region?
Voice incidents rarely respect business hours. If recovery depends on a single team or geographic location, response times will suffer. Teams Direct Routing designs should support distributed ownership and clear escalation paths.
Are compliance controls enforced by default?
Compliance should not rely on manual steps or exceptions. Call recording, data residency, and monitoring requirements should be enforced automatically through the Teams Direct Routing architecture. If controls are optional, risk increases over time.
Are changes tested outside live incidents?
Changes should be validated through routine testing, not during outages. Teams Direct Routing environments that lack regular testing tend to surface defects when pressure is highest.
If any of these questions cannot be answered clearly, the Teams Direct Routing design already carries operational risk.
Teams Direct Routing is often treated as a feature of Microsoft Teams. In practice, it becomes the operating model for enterprise voice once the platform is in production.
Decisions around architecture placement, SBC ownership, and carrier strategy shape how Teams voice performs under load, how resilient it is during outages, and how quickly service can be restored. These choices also determine how much ongoing effort is required to keep the environment secure, compliant, and adaptable to change.
Architecture diagrams show how a solution is intended to work. Day-to-day operations show how it actually behaves. Gaps between the two are where most long-term Teams Direct Routing issues emerge.
When Teams voice fails, the impact is rarely limited to technology. It affects users, support teams, and business operations.
If you want to assess whether your Teams Direct Routing design is built for scale, resilience, and change, speak with our Teams voice experts. We can help you evaluate your current architecture and identify the design approach that best fits your operational and regulatory requirements.