What is Microsoft Teams Phone? Explaining M365 E3/E5 and Teams SKU Differences

About this article
This article reviews official Microsoft Teams Phone licensing and PSTN connectivity information as of September 18, 2026, clarifying the differences between E3/E5 and Teams-included/excluded SKUs.

Verification Status: 📘 Microsoft Official Information Confirmed / Physical Device Unverified

Microsoft Teams Phone is a system that addsPBX (Private Branch Exchange)equivalent capabilities to Teams, allowing organizations to center their internal extensions, main lines, and external calls around Teams.

The most common point of confusion here is thatthe right to use Teams, the Teams Phone system features, and the PSTN services that connect to external telephone networks are all separate layers.

Key Terms to Know First

Checking E3/E5 and Teams SKUs Separately

In current official Microsoft licensing documentation, there are Teams-included and Teams-excluded SKUs, so it is risky to make decisions based solely on the labels "E5" or "E3".

The typical approach is as follows:

Official Microsoft documentation explains a configuration where,if you use Microsoft 365 E5, you do not need to additionally assign Teams Phone Standard on top of it. However, with a Teams-excluded E5, you still need separate usage rights for Teams itself, such as Teams Enterprise.

The Three Layers to Complete Your Telephony

flowchart LR
    U[利用者] --> T[Microsoft Teams利用権]
    T --> P[Teams Phone / Phone System]
    P --> C{PSTN接続方式}
    C --> M[Microsoft Calling Plan]
    C --> O[Operator Connect]
    C --> D[Direct Routing]
    M --> N[PSTN / 一般電話網]
    O --> N
    D --> S[SBC / 既存PBX等]
    S --> N

A Teams Phone license alone does not automatically provide phone numbers or PSTN connectivity. Official Microsoft documentation also states thatthe PSTN solution is separate from the Teams Phone license.

How to Choose a PSTN Connectivity Option

For Direct Routing, Microsoft's updated 2026 documentation specifiesTeams usage rights + Teams Phoneas user requirements. The SBC requires design considerations such as Microsoft-certified/supported configurations, public FQDNs, and certificates.

Try First: Read-Only Verification from the User Side

Before changing production voice routing, verify the calls screen on a test user's Teams client.

1. Open "Calls" in Teams.

2. Check if your phone number is displayed.

3. Verify the workflows for voicemail, forwarding, and missed calls.

4. Record how the policies intended by the administrator appear on the user interface.

What to Look For

• Is a phone number assigned?

• Does the user require outbound external calling?

• Are voicemail and forwarding settings visible?

• Is only internal Teams calling enabled, or is PSTN calling active as well?

Change One Setting

Within the scope permitted to the user, change one low-risk personal setting, such as the voicemail greeting, and verify that the change takes effect. Do not modify number assignments or the organization-wide Voice Routing Policy during initial verification.

Practical Example: Migrating an Existing Main Line to Teams

sequenceDiagram
    participant C as 外部発信者
    participant PSTN as PSTN事業者
    participant TP as Teams Phone
    participant AA as Auto Attendant
    participant U as 担当者Teams
    C->>PSTN: 代表番号へ発信
    PSTN->>TP: Teamsへ着信
    TP->>AA: 代表電話メニュー
    AA->>U: 担当者/Call Queueへ転送
    U-->>C: Teamsから応答

In this scenario, simply assigning Phone licenses to users is not enough. You must design main numbers, Auto Attendants, Call Queues, business hours, emergency calling, and failover routing.

Checklist for General Users, Administrative Staff, and IT Admins

Pay Attention to the Order of Number and License Changes

Microsoft explains that if you remove prerequisite licenses from a user who has an assigned phone number first, the number may be unassigned, impacting inbound and outbound PSTN calls. When switching from E3 to E5, avoid operations like deleting and saving the old license before assigning the new one; instead, pre-verify the migration steps.

Items for Administrators to Verify

• Is the base SKU Teams-included or Teams-excluded?

• Are there Teams usage rights, such as Teams Enterprise?

• Are there Teams Phone/Phone System rights?

• Which PSTN connectivity option will be used: Calling Plan, Operator Connect, or Direct Routing?

• Which carrier will phone numbers be acquired or ported from?

• Are the country/region requirements for Emergency Calling met?

• Have resource accounts for Auto Attendants / Call Queues been designed?

• Has the Voice Routing Policy been inadvertently applied to the organization-wide default?

• For Direct Routing, have the SBC, DNS, certificates, and network been verified?

• Are there requirements for call recording, retention, auditing, or contact center integration?

Common Misconceptions

"With E5, everything including phone numbers and external call charges is included."

Phone System rights and PSTN services are separate. Verify your connectivity option, such as Calling Plan.

"If I add Teams Phone Standard, I can use Teams itself."

Teams Phone requires a prerequisite Teams/Microsoft 365 license. For Teams-excluded SKUs, verify Teams usage rights separately.

"With Direct Routing, I don't need a Teams Phone license."

Microsoft's current requirements for Direct Routing specify that both Teams and Teams Phone are required.

Official Microsoft Information

• Teams Phone licensing

• What is Teams Phone

• PSTN connectivity options

• Plan Direct Routing

When selecting Teams Phone,Teams Usage Rights → Phone System → PSTN Connectivityverifying these three layers separately can reduce licensing errors caused by differences in E3/E5 and Teams SKUs.