You have a Microsoft I earns deployment and an existing telephony solution that provides PSTN capability to on premises third-party PBX systems in two separate locations. You need to implement a…

Question

Options

• Ahighly available Session Border Controllers (SBCs)
• Bcalling policies
• CPSTN usages
• Dvoice routing policies
• Etenant dial plans

• A
  86% (18)
• B
  5% (1)
• E
  10% (2)

Explanation

Implementing a redundant Microsoft Teams Phone PSTN solution via Direct Routing requires three core components that work together to connect, permission, and route calls through your existing infrastructure. Highly available SBCs (A) are the physical/virtual bridge between Teams Phone System and your on-premises PBX/PSTN - deploying them in a redundant, paired configuration at each location ensures outbound calls survive a single component failure. PSTN usages (C) are the permission records that link voice routes to routing policies, and without them no call can traverse a route regardless of SBC health. Voice routing policies (D) are assigned to users and contain those PSTN usages, telling Teams which routes (and therefore which SBCs) to use for outbound calls - enabling failover routing logic when a primary SBC is down.

Calling policies (B) control user features like call forwarding and simultaneous ring - they have no bearing on PSTN routing or redundancy. Tenant dial plans (E) normalize dialed number formats before routing, but they are not required to establish or make redundant a Direct Routing path.

Memory tip: Think of the path a call takes - it leaves through an SBC, is permitted by a PSTN usage, and reaches the user via a voice routing policy. These three form the routing chain; everything else (calling policies, dial plans) is feature configuration layered on top.

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