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 sbc.voice.contos

Question

Exhibit

Options

• AThe certificate does not match the FQDN on the SBC.
• BThe firewall blocks inbound traffic on port 443 to the SBC.
• COnly TLS 1.0 is enabled on the SBC.
• DMicrosoft 365 Phone System licenses are not assigned to the users.

• A
  82% (27)
• B
  3% (1)
• C
  12% (4)
• D
  3% (1)

Explanation

In Microsoft Teams Direct Routing, the SBC must present a valid TLS certificate whose Subject Name (SN) or Subject Alternative Name (SAN) exactly matches the SBC's FQDN (sbc.voice.contoso.com). A certificate mismatch - for example, a certificate issued for a different domain or a wildcard that doesn't cover the SBC's FQDN - causes Microsoft 365 to reject the TLS handshake and logs a certificate warning on the SBC. Port 443 (B) is used for Teams client traffic, not SBC signaling (which uses 5061). Teams Direct Routing requires TLS 1.2 minimum, so TLS 1.0-only (C) would cause a failure but typically a different error. Missing Phone System licenses (D) would block user calls, not generate an SBC certificate warning.

No community discussion yet for this question.