Check your internet connection for Teams Phone System

Teams Phone System is Microsoft's technology for enabling phone capabilities within Microsoft Teams using the Microsoft 365 cloud. Every device that uses Microsoft Teams and Phone System needs a connection to the internet.

To get the best Phone System experience, you need a broadband internet connection that can support the maximum number of phone calls that your organization might make at any one time. You also need to make sure that the computers on your network can reach Microsoft 365 services.

Check your internet connection speed

This article helps determine whether your internet connection is fast enough for the number of people who need to make phone calls. You'll provide information about your organization and get back a report that shows how much of your internet connection will be used by Teams and Phone System.

Gather information about your internet connection and users

Before you start, you need the following information:

  • The speed of your internet connection
  • How many people will use Phone System mainly from your office
  • How many people will use Phone System mainly from a remote location, such as a home office

Enter your information into the network planner

Follow these steps:

  1. In a browser, go to Sign in by using an account that has Global Administrator permissions. The account that you used to sign up for Microsoft 365 has these permissions.
  2. Open Planning and select Network planner.
  3. Under Network plans, select Add. Enter a name for your plan, and then select Apply.
  4. Select the name of your network plan.
  5. On the next page, select Add a network site on the Network sites tab.
  6. Fill in the Network site name, Network Users, and Internet link capacity fields, and then select Save. Leave the other fields on this screen blank, and don't select the ExpressRoute or Connected to WAN options.
  7. On the Report tab, select Start a report.
  8. Enter in a Report name and the number of Network users (Office and Remote), and then select Generate report to create a report that shows the bandwidth requirements for Teams. We will tell you how to read the report in the next section.

Find your minimum internet connection speed

When you select Generate report, Microsoft 365 creates a report.

Under the Impact column and in the Office 365 row, this number shows how much of your internet connection Teams and Phone System will use. We recommend that this number is no more than 30 percent of your total internet connection speed. For example, if your internet connection is 60 Mbps, Teams and Phone System should use no more than 18 Mbps.

Use this equation to determine your minimum internet connection speed: <Impact number> / 0.3.

Let’s say the Impact number is 4.6875 Mbps. The calculation to find your minimum internet connect speed would be 4.6875 / 0.3 = 15.6. In this case, the internet connection speed should be at least 15.6 Mbps.

If Teams and Phone System will use more than 30 percent of your total internet connection speed, the Impact number will appear red. In that case, you may need to upgrade your internet connection.

Connection speed warning.


The bandwidth impact provided by the Network Planner is an estimate only. It is recommended to use Call Quality Dashboard to pro-actively monitor user experience for audio and video calls with Microsoft Teams inside your organization.

Make sure the computers and devices on your network can reach Microsoft 365

Computers and devices that use Phone System must use specific network ports to communicate with Microsoft 365 services. These ports are essentially doors through which devices talk to each other over a network or the internet. Your firewall needs to allow devices on your network to reach Microsoft 365 through the following outbound network ports:

  • TCP ports 80 and 443
  • UDP ports 3478, 3479, 3480, and 3481

The easiest way to check whether your firewall allows communication on these network ports is to perform a connectivity test using the Microsoft 365 network connectivity tool from the office location you want to test. After completing the test, verify the results and recommendations.