- A
Purchase Microsoft 365 E5 add-on for each user
Why wrong: The E5 add-on provides many additional security and compliance features not required, making it more expensive than the targeted add-on.
- B
Purchase Phone System add-on and Audio Conferencing add-on separately for each user
Why wrong: Buying two separate add-ons is more expensive than purchasing the combined 'Phone System + Audio Conferencing' add-on.
- C
Purchase the 'Phone System + Audio Conferencing' add-on for each user
This combined add-on includes both Phone System and Audio Conferencing at a lower cost than purchasing individually.
- D
Upgrade all users to Microsoft 365 E5
Why wrong: Upgrading to E5 is a full license upgrade, which is significantly more expensive than adding the targeted add-on to existing E3 licenses.
MS-900 Describe Microsoft 365 pricing and support Practice Question
This MS-900 practice question tests your understanding of describe microsoft 365 pricing and support. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. A key principle to apply: microsoft Phone System enables PBX capabilities for Microsoft Teams.. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company currently has Microsoft 365 E3 licenses for all 200 users. They need to add PSTN calling capabilities (Phone System and Calling Plan) for making and receiving external phone calls from Microsoft Teams. They also want to allow dial-in audio conferencing for online meetings. They want to minimize additional costs while keeping existing E3 subscriptions. What is the most cost-effective licensing strategy?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"minimum / minimize"Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Purchase the 'Phone System + Audio Conferencing' add-on for each user
Option C is correct because the 'Phone System + Audio Conferencing' add-on is a bundled SKU specifically designed to provide both PSTN calling capabilities (Phone System and Calling Plan) and dial-in audio conferencing for Microsoft Teams at a lower combined cost than purchasing the two add-ons separately. Since the company already has Microsoft 365 E3 licenses, they only need this single add-on per user to meet all requirements without upgrading to E5 or buying individual add-ons, minimizing additional costs.
Key principle: Microsoft Phone System enables PBX capabilities for Microsoft Teams.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Purchase Microsoft 365 E5 add-on for each user
Why it's wrong here
The E5 add-on provides many additional security and compliance features not required, making it more expensive than the targeted add-on.
- ✗
Purchase Phone System add-on and Audio Conferencing add-on separately for each user
Why it's wrong here
Buying two separate add-ons is more expensive than purchasing the combined 'Phone System + Audio Conferencing' add-on.
- ✓
Purchase the 'Phone System + Audio Conferencing' add-on for each user
Why this is correct
This combined add-on includes both Phone System and Audio Conferencing at a lower cost than purchasing individually.
Clue confirmation
The clue word "minimum / minimize" in the question point toward this answer.
Related concept
Microsoft Phone System enables PBX capabilities for Microsoft Teams.
- ✗
Upgrade all users to Microsoft 365 E5
Why it's wrong here
Upgrading to E5 is a full license upgrade, which is significantly more expensive than adding the targeted add-on to existing E3 licenses.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may assume purchasing add-ons separately (Option B) is the most cost-effective because they overlook the existence of a bundled 'Phone System + Audio Conferencing' add-on, which Microsoft specifically offers to reduce costs for organizations needing both capabilities.
Detailed technical explanation
How to think about this question
The 'Phone System + Audio Conferencing' add-on is a single SKU (e.g., SPZA for commercial) that combines the Phone System license (required for PSTN calling) with Audio Conferencing (for dial-in meeting capabilities) and includes a domestic Calling Plan (e.g., 1200 minutes per user per month in the US). Under the hood, this add-on leverages Microsoft's SIP trunking infrastructure and the Teams Direct Routing or Operator Connect for PSTN connectivity, but the bundled SKU simplifies licensing by avoiding separate provisioning of Phone System (e.g., SKU MCOEV) and Audio Conferencing (e.g., SKU MCOMEETADV). A real-world scenario where this matters is when an organization needs to minimize per-user costs while enabling both outbound calling and dial-in conferencing; the bundled add-on is often 20-30% cheaper than purchasing the two add-ons individually.
KKey Concepts to Remember
- Microsoft Phone System enables PBX capabilities for Microsoft Teams.
- Audio Conferencing provides dial-in numbers for Teams meetings.
- The 'Phone System + Audio Conferencing' add-on is for E3 users needing both features.
- This combined add-on is more cost-effective than purchasing Phone System and Audio Conferencing separately.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Microsoft Phone System enables PBX capabilities for Microsoft Teams.
Real-world example
How this comes up in practice
A startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
What to study next
Got this wrong? Here's your next step.
Review microsoft Phone System enables PBX capabilities for Microsoft Teams., then practise related MS-900 questions on the same topic to reinforce the concept.
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FAQ
Questions learners often ask
What does this MS-900 question test?
Describe Microsoft 365 pricing and support — This question tests Describe Microsoft 365 pricing and support — Microsoft Phone System enables PBX capabilities for Microsoft Teams..
What is the correct answer to this question?
The correct answer is: Purchase the 'Phone System + Audio Conferencing' add-on for each user — Option C is correct because the 'Phone System + Audio Conferencing' add-on is a bundled SKU specifically designed to provide both PSTN calling capabilities (Phone System and Calling Plan) and dial-in audio conferencing for Microsoft Teams at a lower combined cost than purchasing the two add-ons separately. Since the company already has Microsoft 365 E3 licenses, they only need this single add-on per user to meet all requirements without upgrading to E5 or buying individual add-ons, minimizing additional costs.
What should I do if I get this MS-900 question wrong?
Review microsoft Phone System enables PBX capabilities for Microsoft Teams., then practise related MS-900 questions on the same topic to reinforce the concept.
Are there clue words in this question I should notice?
Yes — watch for: "minimum / minimize". Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
What is the key concept behind this question?
Microsoft Phone System enables PBX capabilities for Microsoft Teams.
About these practice questions
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Last reviewed: Jun 11, 2026
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