---
title: "MS Teams - Changing your Microsoft 365 Phone System Subscription"
slug: "ms-teams-changing-your-microsoft-365-phone-system-subscription"
tags: ["calltower", "public"]
updated: 2026-09-18T14:20:49Z
published: 2026-09-18T14:20:49Z
canonical: "learn.calltower.com/ms-teams-changing-your-microsoft-365-phone-system-subscription"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://learn.calltower.com/llms.txt
> Use this file to discover all available pages before exploring further.

# MS Teams - Changing your Microsoft 365 Phone System Subscription

**Last updated:** Oct 13, 2025, 10:39 AM by dylan.lewis@calltower.com

## Overview

If you're currently using Microsoft 365 E3 with an add-on Teams Phone System license, upgrading to Microsoft 365 E5 consolidates licensing and ensures your Phone System service remains active. This guide walks you through the upgrade process to prevent potential service disruptions.

## Why Upgrade to E5?

- **Phone System is included** in E5—no need for a separate add-on.
- Avoids accidental removal or expiration of the Phone System license.
- Unlocks additional features like **Microsoft Defender**, **Power BI Pro**, and **Advanced Compliance**.

## Directions

1. In Microsoft 365 Admin, navigate to **Users > Active Users**.
2. Select a user currently assigned E3 + Phone System.
3. Click **Licenses and apps**.
4. Check **Microsoft 365 E5**.
5. Save changes.
6. Uncheck **Microsoft 365 E3** and **Teams Phone System**.
7. Save changes.

## ⚠️Warning: Avoid Configuration Loss⚠️

> [!WARNING]
> Important:
> 
> If you remove the Teams Phone System license **before** assigning the Microsoft 365 E5 license, the user's:
> 
> - **Phone number assignment**
> - **Enterprise Voice configuration**
> - **Calling policies**
> 
> ...may be **automatically wiped** from Teams. This can result in service disruption and require manual reconfiguration.

**To prevent this:**

- Always assign the **Microsoft 365 E5 license first**.
- Only remove the E3 and Phone System licenses **after confirming** E5 is active and applied.