You have a Microsoft Teams Phone deployment. You are deploying Direct Routing. All users have a SIP URI in the format of [email protected]. The Session Border Controller (SBC) is named…

Question

Options

• AThe firewall blocks outbound traffic on port 443 to Microsoft Teams.
• BThe firewall blocks traffic to the signaling port on the SBC.
• CTLS 1.2 is enabled on the SBC.
• DMicrosoft 365 Phone System licenses are not assigned to the users.

• A
  11% (5)
• B
  78% (35)
• C
  4% (2)
• D
  7% (3)

Explanation

Option B is correct because in a Direct Routing deployment, Microsoft Teams must be able to send SIP signaling traffic inbound to the SBC on its configured signaling port (typically TCP/UDP 5067 or 5068 for SIP over TLS). If the firewall blocks this inbound path, the SBC cannot receive call setup messages from Teams, which manifests as SBC-side warnings about failed or dropped connections.

Why the distractors are wrong:

• A is wrong because port 443 is used for HTTPS/management, not Direct Routing SIP signaling; the Teams signaling path uses SIP TLS, not port 443.
• C is wrong because TLS 1.2 is a requirement for Direct Routing - having it enabled is correct, not a problem.
• D is wrong because missing Phone System licenses is a user provisioning issue that would prevent users from being voice-enabled, but it would not generate a network-level warning on the SBC.

Memory tip: Think "two-way street" - Teams must reach the SBC (inbound signaling port) and the SBC must reach Teams. An SBC warning about failed connections almost always points to a firewall blocking inbound SIP traffic to the SBC, not outbound issues from the customer network.

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