Microsoft Teams Phone Licenses Nobody Uses: The Add-on Waste Audit

Voice is the license category where Microsoft 365 waste hides best. A Teams Phone seat is only ~$8/user/month — small enough that nobody questions it, recurring enough that it adds up. Add a calling plan and you're at $15–20/user/month for a capability many of those users never dial. Here are the five patterns we see, and how to audit each one.

Why Teams Phone waste is different

Most license waste comes from inactive users. Teams Phone waste mostly comes from stalled projects: a PBX migration that covered the pilot group and then paused, a "future voice rollout" that justified buying licenses org-wide, a departed telecom champion. The users are active — in Teams, in Outlook — so a normal inactivity audit sails right past them. You have to check the voice layer specifically.

Pattern 1: License assigned, no phone number attached

A Teams Phone license does nothing until a phone number is assigned to the user. Licenses bought in bulk for a migration that stalled sit in exactly this state — paid, assigned, and incapable of making a PSTN call.

How to check: in the Teams admin center, compare Voice → Phone numbers against your Teams Phone license assignments. Or in PowerShell: Get-CsOnlineUser and filter licensed users where LineURI is empty. Every match is pure waste — not underused, unusable.

Pattern 2: Number assigned, nobody calls

The user got a number in the 2023 migration and has made zero PSTN calls since. Teams-to-Teams calls are free VoIP and don't need the license — what you're paying for is the dial tone to the outside world.

How to check: Teams admin center → Analytics & reports → Usage reports → PSTN and SMS usage. Export 90 days, group by user, and list licensed users with zero outbound PSTN calls. For anyone on a per-user calling plan on top of the base license, the meter runs twice: base seat plus bundled minutes nobody consumes. Consider moving light callers to pay-as-you-go calling before cutting seats entirely.

Pattern 3: The E5 double-pay

Microsoft 365 E5 includes Teams Phone. Tenants that upgraded a group to E5 after an earlier standalone Teams Phone purchase routinely keep paying for both — the add-on assignment doesn't error, it just silently duplicates.

How to check: intersect your E5 assignment list with your standalone Teams Phone assignments. Every user on both lists is an immediate, zero-risk removal. (Same logic applies to legacy Audio Conferencing add-ons — Microsoft has bundled audio conferencing into most enterprise suites since 2022, and old à-la-carte purchases linger.)

Pattern 4: Full user licenses on lobby phones

Conference rooms, lobby handsets, warehouse phones — devices, not people. They need the Teams Shared Devices license (~$8/month), not an E3 + Teams Phone stack that can run $44+/month. A tenant with a dozen common-area devices on full user licenses is burning $400+/month on hardware that makes three calls a day.

How to check: look for user accounts named after rooms or locations holding full suites. They're easy to spot by name and rarely have sign-in activity that matches a human.

Pattern 5: Departed users' voice stack

Offboarding checklists usually catch the E3. They rarely catch the voice add-ons stacked on top — Teams Phone, calling plan, sometimes a dedicated number kept "just in case". Numbers can be unassigned and returned (or reassigned) without keeping the license alive.

How to check: disabled accounts with any voice add-on. This is the disabled-accounts audit with a voice filter on it.

Run it as one audit

Manually, this is four exports (license assignments, phone-number inventory, PSTN usage, account status) joined in a spreadsheet — an afternoon of work, and worth it before your renewal. See the full renewal checklist for the other nine checks.

Automatically: SeatPrune syncs license assignments and per-service usage from your tenant daily and prices each finding in $/month, so the Teams Phone line on your renewal is a decision, not a rollover.

The test for any voice license is one question: did this seat touch the PSTN in the last 90 days? If the answer is no and there's no dated plan for it, reclaim it — Teams-to-Teams calling still works without it.