You are planning a Microsoft Teams Phone deployment that will use Direct Routing. You need to allow traffic from Microsoft 365 to a Session Border Controller (SBC). Which IP address ranges should…

Question

Options

• A8.8.8.8/32 and 4.4.2.2/32
• B52.112.0.0/14 and 52.120.0.0/14
• C132.245.0.0/16 and 40.104.0.0/15
• D10.10.0.0/24 and 10.11.0.0/24

• A
  3% (1)
• B
  89% (32)
• C
  3% (1)
• D
  6% (2)

Explanation

Option B (52.112.0.0/14 and 52.120.0.0/14) is correct because these are the Microsoft-owned public IP ranges specifically designated for Teams media transport, which is what Direct Routing uses to carry signaling and media between Microsoft 365 and your SBC. Without allowing these ranges through the firewall, the SBC cannot establish the SIP trunk or pass voice traffic to the Microsoft Phone System.

Why the distractors are wrong:

• A (8.8.8.8 and 4.4.2.2) are Google's public DNS servers - completely unrelated to Microsoft infrastructure.
• C (132.245.0.0/16 and 40.104.0.0/15) are legitimate Microsoft 365 IP ranges, but they serve Exchange, SharePoint, and general O365 traffic - not Teams media/signaling for Direct Routing.
• D (10.10.0.0/24 and 10.11.0.0/24) are private RFC 1918 addresses, which are non-routable on the internet and would never be source addresses coming from Microsoft's cloud.

Memory tip: Think "52 for SIP" - both Teams Direct Routing ranges start with 52, and they come in a pair of /14 blocks (52.112 and 52.120). If you see a Microsoft Teams Phone firewall question and the answer has two 52.x ranges, that's your signal.

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