MS-900 Practice Question: A company with 100 users has Microsoft 365…

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✗

  Upgrade all users to Microsoft 365 E3 and add Phone System and Audio Conferencing.

  Why it's wrong here

  Upgrading all 100 users to Microsoft 365 E3 does not in itself provide the desired voice capabilities; you would still have to add Phone System and Audio Conferencing as separate per-user add-ons. E3 also includes enterprise-grade security and compliance features that a 100-person business likely does not need, so you would be paying for unused functionality before even paying for telephony. The total licensing cost is dramatically higher than simply adding Microsoft 365 Business Voice to the existing Business plan, and it introduces a complex license migration for no procurement benefit.

• ✓

  Add the Microsoft 365 Business Voice add-on for each user.

  Why this is correct

  Microsoft 365 Business Voice is a single add-on SKU that bundles Phone System, Audio Conferencing, and a domestic Calling Plan for users on Microsoft 365 Business Basic, Standard, or Apps. It gives Teams full PBX features, dial-in meeting numbers, and PSTN calling without requiring a plan upgrade or separate telephony components. For this scenario, adding Business Voice to each of the 100 existing Business users is the most direct, economical path because it is purpose-built for small and mid-size businesses and avoids purchasing each voice capability individually.

• ✗

  Purchase Phone System and Audio Conferencing as standalone add-ons separately.

  Why it's wrong here

  Purchasing Phone System and Audio Conferencing as standalone add-ons is technically valid, but it is more expensive because the two SKUs are billed independently and Phone System alone does not include PSTN calling minutes. You would also need a Calling Plan (or an operator connect service) as a third purchase to enable external calls, turning one intended voice rollout into three separate licensing decisions. The Business Voice bundle exists specifically to consolidate those component costs into one lower-priced per-user license, so this a la carte approach is neither the simplest nor the cheapest option.

• ✗

  Add the Microsoft Teams Phone Standard add-on.

  Why it's wrong here

  Teams Phone Standard is the newer name for the Phone System add-on, but it does not include Audio Conferencing. You would still need to add Audio Conferencing separately, making it more expensive than the Business Voice bundle.

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