Microsoft 365 E5 includes the Teams Phone phone system, so teams that want to make and receive outside calls in Teams often assume the whole company has to move to E5. It does not. Microsoft 365 E3 is $39/user/month and Microsoft 365 E5 is $60/user/month on an annual commitment, so the E5 upgrade costs $21/user/month.
But the phone system itself is also sold separately as Microsoft Teams Phone Standard at $10/user/month on an annual commitment. E3 plus that add-on is $49/user/month — $11 less per phone user per month than E5. For 20 staff who actually need an outside line, that is $220/month, $2,640/year, for the identical phone system. And only the people who need a phone line need the add-on at all — everyone else stays on plain E3.
The math
| Measure | Amount |
|---|---|
| Microsoft 365 E3 | $39/user/mo |
| Microsoft 365 E5 | $60/user/mo |
| Microsoft Teams Phone Standard add-on | $10/user/mo |
| E3 + Teams Phone Standard | $49/user/mo |
| 20 phone users on E3 + Phone Standard | $980/mo = $11,760/year |
| 20 phone users on E5 | $1,200/mo = $14,400/year |
| Saving | $220/mo = $2,640/year ($132/year per phone user) |
The decision rule
- Staff need outside calling but not E5's security, compliance, or analytics stack → E3 + Teams Phone Standard is the honest buy.
- Staff also genuinely need E5's Defender Plan 2 suite, Power BI Pro, or Purview premium compliance → E5 is the honest buy, and the phone system is a bonus, not the reason.
- Nobody on the team needs an outside line → buy no phone license at all; Teams-to-Teams calling needs no add-on.
Step by step
- Count who actually needs an outside line. List the staff who make or receive calls to real phone numbers — not everyone who uses Teams chat and meetings.
- Keep those users on E3 and add Microsoft Teams Phone Standard ($10/user/month) to just those users in the Microsoft 365 admin center.
- Add PSTN connectivity separately — this is the step people miss. Teams Phone Standard is the phone system only; it carries no phone number or minutes. Pair it with a Microsoft Calling Plan, Operator Connect, or Direct Routing. Note this cost applies under E5 too, since E5 includes the phone system, not a calling plan, so it does not change the comparison.
- Leave everyone else on plain E3 with no phone add-on.
- Revisit at renewal: if the security or analytics case for E5 becomes real, re-run the E5 math then — do not pre-buy it for the phone system alone.
20 phone users on E3 + Teams Phone Standard instead of E5.
For the license assignment (PSTN setup is separate).
Prices verified October 28, 2026: Microsoft 365 E3 $39/user/month and E5 $60/user/month on an annual commitment, per Microsoft's enterprise plans and pricing page; Microsoft Teams Phone Standard $10/user/month on an annual commitment, phone system only with PSTN service via Calling Plans, Operator Connect, or Direct Routing, and Teams Phone included in Microsoft 365 E5, per Microsoft's Teams Phone page and E5 page.
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