You have a Microsoft Teams Phone deployment. You need to implement PSTN connectivity by using Direct Routing. What are three requirements for the implementation? Each correct answer presents part of…

Question

Options

• Aa Session Border Controller (SBC) that uses a hostname in the onmicrosoft.com domain
• Ba firewall rule that opens a TCP signaling port to Microsoft Teams
• Ca public DNS entry that maps the FQDN of the Session Border Controller (SBC) to a public IP
• Da firewall rule that opens a UDP signaling port to Microsoft Teams
• Ea Teams-certified Session Border Controller (SBC)

• A
  8% (3)
• B
  87% (34)
• D
  5% (2)

Explanation

Direct Routing requires a Teams-certified SBC (E) because Microsoft maintains an approved vendor list to ensure interoperability and security - uncertified devices are not supported. A public DNS entry mapping the SBC's FQDN to a public IP (C) is mandatory so Microsoft's infrastructure can resolve and reach your SBC from the internet. A firewall rule opening the TCP signaling port (B) is required because Direct Routing uses SIP over TLS, which is TCP-based (port 5061) - not UDP.

Why the distractors fail:

• A is wrong because the SBC's FQDN cannot use the .onmicrosoft.com domain; it must use a custom domain verified in your Microsoft 365 tenant.
• D is wrong because SIP signaling in Direct Routing travels over TCP (TLS), not UDP. UDP is used for media (RTP/SRTP), not signaling - so a UDP signaling rule is incorrect.

Memory tip: Think "TCE" - TCP port, Custom DNS, E-certified SBC. If you remember that Direct Routing is built on TLS/TCP signaling (not UDP), requires a public resolvable name, and demands a certified device, the three correct answers follow naturally.

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