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
  6% (2)
• B
  91% (29)
• D
  3% (1)

Explanation

Direct Routing has three core infrastructure requirements: (1) A Teams-certified SBC (E) - Microsoft maintains a list of certified SBCs; only these are supported for Direct Routing. (2) A public DNS record (C) - the SBC's FQDN must resolve to a public IP address so Microsoft's infrastructure can reach it; without this, the TLS handshake and SIP registration will fail. (3) A TCP-based firewall rule (B) - Direct Routing uses SIP over TLS on TCP port 5061 for signaling between the SBC and Microsoft's SIP proxy; UDP is used for media (RTP/SRTP) but not for signaling. Option A is wrong because the SBC must use a publicly registered domain, not onmicrosoft.com (that domain is reserved for Microsoft's own services). Option D is wrong because SIP signaling in Direct Routing uses TCP, not UDP.

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