Microsoft MS-721 Exam Practice Questions, practice question pack
MICROSOFT · MS-721

Microsoft MS-721 Exam Practice Questions

300 questionsPDF by emailUpdated September 2026

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Three of the 300 questions in this pack

Question 1

You have a Teams Phone deployment that uses Direct Routing on a single Session Border Controller (SBC). Users report that outbound PSTN calls are failing, but inbound PSTN calls are successful. When you review the SBC logs, you discover that Microsoft is responding to SIP option requests, but is NOT sending SIP option requests. What is the cause of the issue?

  1. The online PSTN gateway is disabled.
  2. An SBC certificate is expired.
  3. An external DNS entry is missing from the FQDN of the SBC.
  4. The phone numbers of the users are defined by running the New- csTeamsUnassignedNumberTreatment cmdlet.
Show answer and explanation

Correct answer: C. An external DNS entry is missing from the FQDN of the SBC.

the SBC. When Microsoft cannot send SIP OPTIONS requests to the SBC, it indicates a connectivity issue from Microsoft's side. An external DNS entry for the SBC's FQDN is required for Microsoft to locate and communicate with the SBC. Without proper DNS resolution, Microsoft cannot initiate outbound SIP OPTIONS requests, though inbound calls may still succeed if they're routed through different pathways. This explains the asymmetric call flow where inbound works but outbound fails.

Why the other options are wrong

  • A. If the PSTN gateway were disabled, both inbound and outbound calls would fail, not just outbound.
  • B. An expired certificate would affect both inbound and outbound call establishment, not selectively prevent Microsoft from sending SIP OPTIONS.
  • D. Unassigned number treatment affects how calls to unassigned numbers are handled, not the ability to make outbound calls for assigned users.

Question 2

The sales department at your company needs to route a call to multiple users and have calls route differently after business hours. Which two features should you implement? Each correct answer presents part of the solution. NOTE: Each correct selection is worth one point.

  1. call queues
  2. calling policies
  3. voice routing policies
  4. auto attendants
  5. caller ID policies
Show answer and explanation

Correct answer: A, D

A. call queues D. auto attendants Auto attendants handle call routing based on time-of-day rules, enabling different routing after business hours. Call queues route calls to multiple users within a department and support agent availability configurations. Together, these features allow the sales department to route calls to multiple users during business hours and implement different routing logic after hours. Call queues provide the multi-user routing, and auto attendants provide the time-based routing logic.

Why the other options are wrong

  • B. Calling policies control whether users can make outbound calls and receive inbound calls, not how calls are routed between multiple users.
  • C. Voice routing policies determine which PSTN gateway or route is used for calls, not how calls are distributed among multiple recipients.
  • E. Caller ID policies control what caller ID information is displayed, not call routing logic.

Question 3

You have a Microsoft Teams Phone deployment. You are deploying Direct Routing by using a certified Session Border Controller (SBC). The FQDN of the SBC is sbc1.contoso.com. You use signaling port 5067. You cannot place calls and receive an error message in the Microsoft Teams admin center as shown in the following exhibit. What is a possible cause of the issue?

Exhibit for question 3

  1. Calling plan licenses are not assigned to users
  2. The failover timer is set to 0 seconds
  3. The Forward P-Asserted Identify (PAI) header is disabled
  4. The Baltimore or the Digicert root certificates are missing on the SBC.
Show answer and explanation

Correct answer: D. The Baltimore or the Digicert root certificates are missing on the SBC.

missing on the SBC. The exhibit shows 'TLS connectivity status: Inactive,' which indicates a failure in the TLS handshake between Teams and the SBC. This occurs when the SBC cannot present valid certificates during the TLS negotiation. Microsoft Teams requires the SBC to present certificates signed by trusted certificate authorities, specifically Baltimore or Digicert root certificates. If these root certificates are missing from the SBC's certificate chain, the TLS connection cannot be established, resulting in the inactive status shown. Without successful TLS connectivity, signaling cannot occur, preventing calls from being placed or received.

Why the other options are wrong

  • A. Calling plan licenses affect user ability to make calls but would not cause a TLS connectivity status error at the SBC level.
  • B. The failover timer setting controls retry behavior for SBC connections but does not directly cause TLS connectivity failures.
  • C. The PAI header configuration affects call routing and identity information but is not related to TLS connectivity status.

See all 10 free questions Get the full pack, US$39

300 practice questions for Collaboration Communications Systems Engineer (MS-721), with full explanations.

Every question comes with the correct answer, the reasoning behind it, and a short note on why each wrong option is wrong. Work through it once with the answers, then again with the questions-only copy under exam conditions.

  • 300 questions mapped to the MS-721 exam objectives
  • Answers and explanations for every question, including the wrong options
  • A questions-only PDF for timed practice runs
  • Instant delivery by email the moment you check out
  • Free monthly updates for as long as the exam is live
  • Pass or your money back

An MS-721 attempt costs US$165 in the US. This pack is US$39, paid once.

Try 10 questions free before you buy.

Last updated September 2026 · 300 questions

What makes the MS-721 hard

MS-721 is the deep-voice sibling of MS-700: where the Teams admin exam touches telephony, this one lives in it, and telephony is where generalist M365 admins run out of road.

The bank is dominated by voice engineering decisions: Direct Routing SBC configuration and certificate requirements, Calling Plans versus Operator Connect trade-offs, dial plans and normalisation rules, emergency calling with dynamic locations, and auto attendant and call queue design. Then the rooms layer: Teams Rooms deployment, device management, and the meeting-quality troubleshooting workflow through CQD.

Teams Phone alone is 30 to 35% of the exam, the single heaviest domain, with planning and design another 20 to 25%. It is a smaller candidate pool than MS-700, but a far more specialised one, with prep material to match.

About the exam

MS-721 certifies planning and managing Teams collaboration communications: Teams Phone with Direct Routing, Operator Connect and Calling Plans, meeting rooms and devices, and voice troubleshooting. Skills measured as of 28 April 2026. Renews annually via a free online assessment.

Exam domains

  • Plan and design collaboration communications systems: 20 to 25%
  • Configure and manage Teams meetings, webinars, and town halls: 15 to 20%
  • Configure and manage Teams Phone: 30 to 35%
  • Configure and manage Teams Rooms and devices: 20 to 25%

Around 40 to 60 questions, 100 minutes, passing score 700 out of 1000, US$165 in the US, priced by local currency elsewhere, online proctored or test centre, renews annually for free.

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Questions before you buy

What do I get when I buy the Microsoft MS-721 pack?

300 practice questions as a PDF, each with the correct answer, a full explanation and a note on why the other options are wrong, plus a separate questions-only PDF for timed practice.

How quickly do I receive it?

Your PDF is prepared and sent to your email address after checkout, and you get a confirmation as soon as it is on its way.

Is there a free sample?

Yes. Ten questions from this pack, with answers and explanations, are free on this page and as a PDF, so you can judge the quality before you pay.

Are updates included?

Yes. The pack is updated every month for as long as the exam is live, and updates are free for everyone who has bought it.

What if I fail the exam?

We refund the pack. Sit the exam 7 to 30 days after buying, then send your official score report within 7 days of the exam date, as set out in the refund policy.

Can I share it with colleagues?

Each purchase is licensed to one person. For a team, school or training organisation, email support@certstash.com for a licence that fits.

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