Understand calling in Microsoft Teams

In this training, we introduce calling capabilities in Teams, which are powered by the Phone System feature in Office 365. We’ll explain the technical planning that’s required to implement Phone System, how to configure it, and how to monitor usage and call quality in your implementation.

This training is for you if you're:

  • An IT pro.

  • Responsible for planning, deploying, or managing Teams.

  • Planning to introduce calling capabilities in your Teams deployment.

You’ll learn:

  • What is calling in Teams?

  • How to plan for calling in Teams.

  • How to configure calling in Teams.

If you have any questions or feedback about this training, please:

  • Post in the comments section at the bottom of the 'next steps' page of this tutorial

  • Email us at AskTeams@microsoft.com

To give us product feedback about Teams, such as ideas for new features, please visit UserVoice.

You will learn how to...

What is calling in Teams?

Out of the box, Teams supports the ability for users to make voice over IP (VoIP) calls from Teams client to Teams client.

With Phone System with Calling Plans, users can make, receive, and transfer calls to and from landlines and mobile phones on the public switched telephone network (PSTN).

Action: Watch Calling in Teams (3:00 minutes)

Calling features in Teams

Calling in Teams supports basic Phone System features, such as call answering and initiating (by name and number) with integrated dial pad, call holding and retrieving, call forwarding and simultaneous ringing, call history, voicemail, and emergency calling.

More advanced features will be added over time. For more information, see Skype for Business to Microsoft Teams Capabilities Roadmap.

Calling in Teams is powered by Phone System (formerly known as Cloud PBX), the same service in Office 365 that enables PSTN calling capabilities in Skype for Business Online.

Important: Note that the Phone System feature set for Skype for Business is different from the Phone System feature set for Teams.

Action: To understand which features are currently available and the timelines for features that we expect to develop, see the following resources:

  • On the public roadmap, review the “Calling roadmap” slide for an overview of the expected timelines for feature release dates.

  • Review Here’s what you get with Phone System in Office 365 for a description of Phone System features. Keep in mind that at this writing, some of these features might only be available for Skype for Business.

Emergency Services calling

It’s important that you understand how the Emergency Services calling feature operates differently in Teams than in traditional telephone services. You must make sure your users also understand those differences. For example, when they use Teams to call emergency services (such as 911 in the United States), users need to be aware that Teams might not be able to determine the actual location of the caller.

Action: Review Emergency calling terms and conditions for detailed information about Emergency Services calling.

Considerations for Skype for Business Online customers

If you aren’t using Skype for Business Online, you can skip this section. For those who are familiar with the calling feature in Skype for Business Online, we want to highlight some important points.

  • Calling Plans is the only way to connect to the PSTN.
    In contrast to Skype for Business Online, the only way to use Teams to connect to the PSTN is by using Calling Plans (formerly known as Cloud PBX with PSTN Connectivity), where Microsoft provides all phone services including the PSTN numbers. Other options, such as leveraging an existing PSTN infrastructure through a Skype for Business pool or Cloud Connector Edition, don’t exist at this time.

  • Features are different between Skype for Business and Microsoft Teams.
    Note that the calling features in Skype for Business and Microsoft Teams are different. Don’t assume that just because one of the clients is capable of something, the other client can do it as well.

  • Calls can be received either in Teams or Skype for Business, but not both.
    If you configure your users for Phone System with Calling Plans, they can initiate calls from either Teams or Skype for Business. However, they can only receive calls on one of the applications—to configure which application receives calls, you use a new policy, CsTeamsInteropPolicy. You’ll learn more about the policy later in this training.

  • Calls can be made either from Skype for Business or Teams, if you’ve configured Phone System in Teams.
    Except for the aforementioned configuration of the CsTeamsInteropPolicy, the configuration is the same in Skype for Business and Teams. This means that if you’ve already configured calling for Skype for Business, your users will be able to place calls from Teams.

Practical guidance

Microsoft provides practical guidance that takes you through the Office 365 FastTrack customer journey framework and its three phases—Envision, Onboard, and Drive Value—to help you plan, deliver, and operate a successful Phone System with Calling Plans implementation.

The goal of the practical guidance is to set your project up for success, not only from a technical perspective (that is, delivering a reliable, high-quality implementation) but also making sure that the solution meets the requirements of the project stakeholders.

There’s a feedback loop between practical guidance and technical planning:

  • You need to understand the features and capabilities of Phone System to understand how it can support your business use cases.

  • You need to define your business use cases to understand how to best configure Phone Systems.

This means you might have to adjust this practical guidance to meet your objectives. You’ll be asked to complete the following tasks:

  • Define business use cases for Phone System with Calling Plans Document expected, measurable business outcomes, including the following:

    • Description of your current business process

    • Challenges with your existing business process

    • How technology can help overcome these challenges

    • The expected, measurable business outcomes if these challenges are overcome

  • Identify key stakeholders
    Based on your business use cases, create a comprehensive list of stakeholders, including roles and descriptions. This helps you identify everyone involved in the project.

  • Define objectives and key results (OKRs), key success indicators (KSIs), and risks
    Use OKRs and KSIs to set clear goals for measuring the success of the project, and review them regularly to measure progress. It’s important that the stakeholders are aware of and agree to the OKRs and KSIs to work toward a common goal. In addition, you need to identify and document risks to raise awareness, and be prepared to mitigate them as needed.

  • Assess your environment and evaluate adoption readiness
    After you know what you want to achieve and have documented your OKRs and KSIs, assess whether your organization is ready to leverage the service and whether it can provide all the features your users need.


Assessing the environment also includes conducting a readiness assessment for your network. Don’t underestimate the importance of networking: network quality directly affects the user experience. Even if you’ve never had problems with your network, real-time communication might behave differently from other applications. Especially when it comes to telephony, users have high expectations for great quality. Having network quality challenges—especially in the beginning of a project like this—might put the whole project at risk.

  • Map operational roles
    After the solution is rolled out, you’ll need someone to monitor and drive usage and quality. Mapping operational roles upfront helps you to identify the people you’ll need.

  • Create a success plan
    The success plan gives the project team—which can include FastTrack or a deployment partner—enough information to realize the organization’s goals with Phone System with Calling Plans. It should contain the following sections:

    • Business case

    • Service readiness

    • Adoption plan

    • Operational plan

Additional information: For more details about this practical guidance and templates you can use in your planning, see Practical Guidance for Phone System with Calling Plans in Microsoft Teams.


To plan for the implementation of calling in Teams, a series of decisions must be made to better prepare your organization to meet business requirements. These include:

  • Connecting to the PSTN

  • Service availability and user locations

  • Phone System licensing

  • Phone numbers and emergency locations

  • Voicemail

  • Optional: Calling identity

  • Optional: Dial plans

Connecting to the PSTN

In order for users to place and receive calls to the PSTN by using Teams, you need to have installed Phone System and you need to connect phone system to the PSTN.

To better understand how Phone System and the connection to the PSTN work together, imagine you’re buying a mobile phone. The phone has nice features (such as buttons and apps), but to make calls you’ll need to have a call plan with a phone provider, who gives you an actual phone number and provides connectivity to the PSTN.

Phone System is the equivalent of the mobile phone: it provides you with functionality such as voicemail, but neither gives you a phone number nor lets you place or receive phone calls to or from the PSTN. For connecting Phone System to the PSTN—the equivalent of a contract with a phone provider—Microsoft offers Calling Plans, in which Microsoft provides each user a phone number that can place and receive calls.

Currently, Calling Plans are the only way to connect Phone System to the PSTN. In the future, you’ll have the option to connect any existing telephone environment that you have on-premises to Teams.

Service availability and user locations

Phone System is available where Office 365 is available (for the complete list of countries and regions, see International availability). The availability of the Calling Plans service is a little more restricted. The commercial availability of Phone System and Calling Plans also depends on where your organization is based—and, more importantly, in which country or region your organization has a commercial relationship with Microsoft and its partners:

  • Calling Plans can be assigned and used only for users located in countries where calling plans are available.

  • Calling Plans can only be purchased if your billing address is located in a country or region where Audio Conferencing can be purchased.

Example 1
Contoso’s billing address is in Austria, and the company wants to use Phone System with Calling Plans for their users in Germany. Although the Calling Plans are available in Germany, they aren’t available in Austria. However, Audio Conferencing can be purchased in Austria, so Contoso can buy the required licenses for their users in Germany.

Example 2
Fabrikam, Inc. is a company based out of Hong Kong, with some users in the United States. Their billing address is in Hong Kong. Although Microsoft can provide a phone number for Audio Conferencing in Hong Kong, Audio Conferencing isn’t available for purchase in that region. Unfortunately, this means that Fabrikam won’t be able to acquire Calling Plans for their US-based users.

Action: Review Country and region availability for Audio Conferencing and Calling Plans for the following information:

  • For the country where your billing address is located, check whether Audio Conferencing is available for purchase. This will determine whether you can buy any Calling Plans at all.

  • For every country or region where you want users to leverage Calling Plans, check “Is Phone System available for purchase?” to learn whether Calling Plans are available in that country or region.

Phone System licensing

A Phone System license is available as part of Office 365 E5 subscription plans, or as an add-on service to Office 365 E1 or Office 365 E3 subscription plans.

Calling Plans is an add-in to the Phone System feature in Office 365. This means that a Phone System license is the prerequisite for users to be enabled for Calling Plans.

In general, there are two types of Calling Plan add-ins:

  • Domestic Calling Plan

  • International and Domestic Calling Plan

Each Calling Plan type provides an allocation for calling minutes that users can use per month, either to make domestic calls or international calls. The number of minutes varies by country. After their allocation is exhausted, users won’t be able to make outbound calls—except for Emergency Services calling—until the next month’s billing cycle.

As you might expect, a Domestic Calling Plan costs less than the International and Domestic Calling Plan. Typically, not everyone in an organization needs to make international calls. You can assign individual users to different calling plans based on the user’s business requirements. This flexibility can help you control the costs of your Phone System with Calling Plans implementation.

You can set up Communications Credits so that users can make calls even after they’ve used up their minutes, without their having to wait until the next month’s billing cycle. This means that as soon as your allocation is exhausted, you can pay based on your consumption. You can also use Communications Credits to let users who have been assigned to a Domestic Calling Plan make international calls, which are then charged by using a “pay-per-minute” model.


Additional information

Phone numbers and emergency locations

For Phone System with Calling Plans implementation, every user in your organization needs to have a unique subscriber (user) phone number. Subscriber (user) phone numbers can be obtained directly from Microsoft, or existing phone numbers can be transferred (ported) to Microsoft.


The complexity of obtaining or transferring phone numbers varies greatly depending on country/region, carrier, number of circuits involved, and many other contributing factors.

In addition to ensuring that every user has a unique phone number, you must assign an emergency address to each phone number—either when you assign the phone number or when you first acquire it, depending on your country/region. The emergency address is required to support emergency services calling. It must be validated to ensure the address is recognized and it’s in the correct format for emergency response services to use.

To give emergency responders more exact information about the location of your users, you can define emergency locations and associate them with validated emergency addresses. An emergency location is typically a building number, floor, building wing, or office number where the user is located.

Additional information


Phone System voicemail, powered by Azure Voicemail services, supports voicemail deposits to Exchange mailbox only and doesn’t support third-party email systems.

By default, Phone System voicemail works with Exchange Online; however, it has a minimum supported Exchange on-premises version and deployment model to allow delivery of voicemail messages to user mailboxes in the on-premises Exchange deployment.

Phone System voicemail includes voicemail transcription, which is enabled for all users in your organization by default. Your business might require that you disable voicemail transcription for specific users or everyone throughout the organization.


A fallback mechanism has been implemented so that Phone System voicemail can resend messages by using SMTP, which means users who have a mailbox on a third-party email system will receive their voicemail messages. This mechanism doesn’t include guaranteed service uptime or other voicemail features such as changing voicemail greetings.

Additional information

Optional: Calling identity

By default, all outbound calls use the assigned phone number for the calling identity (Caller ID). The recipient of the call can quickly identify the caller and decide whether to accept or reject the call.

In some cases, there are legitimate business reasons to display a different number to mask the identity of a caller.

Contoso is using Phone System with Calling Plans for their users. However, their business requirement demands that if the receptionist calls a phone number, the caller ID shouldn’t represent the phone number of the receptionist but rather the main phone number of the office.

Other options are the possibility to block (anonymize) Caller ID presentation altogether, or give users the choice of using their caller ID or calling out anonymously.

Caller ID can also be blocked for incoming calls.

Additional information

Optional: Dial Plans

A Dial Plan in the Phone System feature of Office 365 controls how users dial phone numbers on the dial pad. The PSTN expects phone numbers in a specific format that starts with a plus sign (+) followed by digits that represent an E.164 number. E.164—the standard for PSTN numbers—specifies country codes.

Obviously, users prefer not to use that long format when dialing phone numbers. Especially when they’re calling a local number, they want to proceed without a country code and maybe even without an area code. This is where dial plans come in: you can use them to normalize a user-entered phone number to the required format.

Example 1
Alice wants to call the phone number +1 311-555-2368. Because Alice is in the United States, based out of Seattle (area code 206), she only needs to dial 311-555-2368. Teams will normalize this phone number to the full number +1 311-555-2368 before routing it to the PSTN.

By default, a generalized dialing behavior is implemented by the automatically assigned Dial Plan (also known as a service dial plan) based on each individual user’s license usage location. This generalized dialing behavior might not meet user requirements—for example, it might require the user to dial an area code to make local calls. In such a case, you’ll need a customized Dial Plan (also known as a tenant dial plan) so users can dial phone numbers the way they’re accustomed to, such as omitting the area code for local calls or using short-digit dialing to call other users in the same location or office.

Example 2
Bob also wants to call the phone number +1 311-555-2368. Bob is not only in the United States, he’s actually located in the 311 area code. He expects to be able to place the call by dialing 555-2368. You can configure Teams to accommodate Bob’s dialing behavior and normalize the phone number to the correct format before sending it to the PSTN.

You can assign different dial plans to different users. This way, you can create a specific experience matching the different requirements of your users, for example if users in a particular location want a dialing experience that’s different from users in another location.

Additional information

  • For a readiness session training on dial plans, go to Tenant Dial Plans. Although this training was created for Skype for Business, it applies to Teams as well because it’s built on the same infrastructure.


To set up Phone System with Calling Plans in Teams, follow these steps:

  1. Enable Exchange on-premises for Azure Voicemail

  2. Validate required licenses

  3. Assign licenses

  4. Acquire phone numbers

  5. Set up emergency addresses and locations

  6. Assign phone numbers and emergency addresses to users

  7. Optional: Assign Calling Identity settings to users

  8. Optional: Assign Dial Plan settings to users

  9. Assign Teams Calling interop policy

For a walkthrough of the onboarding process, watch the following video:

1. Enable Exchange on-premises for Azure Voicemail

If some of your users have their Exchange mailbox on an Exchange Server on-premises, follow the steps in Azure PBX voicemail support for Exchange Server to enable it for working with Azure Voicemail.

2. Validate required licenses

From the Envision phase, you should have a list of the licenses that make up the prerequisites for the implementation of Phone System with Calling Plans for your organization:

  • Microsoft Teams

  • Skype for Business Online (Plan 2)

  • Phone System

  • Domestic Calling Plan, or Domestic and International Calling Plan

  • Communications Credits (optional)


Phone System license can be obtained as part of Office 365 Enterprise E5 subscription plan or as an add-in for Office 365 Enterprise E1 or E3.


If the required licenses aren’t available, you need to consult the team in your organization responsible for Office 365 subscriptions so that they can procure the required licenses.

3. Assign licenses

After you’ve confirmed that the required licenses (based on your implementation plan) are available, you need to assign the licenses to users.

Follow the instructions in Assign Skype for Business and Microsoft Teams licenses to perform license assignment for individual or multiple users by using the Skype for Business admin center or a remote PowerShell session.

4. Acquire phone numbers

Getting phone numbers for a Phone System with Calling Plans implementation can be accomplished in multiple ways:

  • Acquire phone numbers by using the Skype for Business admin center (United States and United Kingdom only)

  • Request phone numbers by submitting a phone number request form

  • Transfer (or port) existing phone numbers to Microsoft

5. Set up emergency addresses and locations

Follow the instructions in Add or remove an emergency address for your organization, to set up emergency addresses and locations. For more information, see

6. Assign phone numbers and emergency address to users

Follow the instructions in Assign, change, or remove a phone number for a user, to assign phone numbers and emergency addresses to users.


For the assigned phone numbers to show up in Teams, you must update the user’s office phone number in Azure Active Directory (Azure AD). You can edit this attribute in the Office 365 Admin center if the user was created directly in Office 365 or Azure AD). If the user is synchronized from on-premises Active Directory, you must use on-premises Active Directory to update the office phone number attribute.

7. Optional: Assign Calling Identity settings to users

Based on your implementation plan, you might need to configure the Calling Identity settings for your users. Follow the instructions in Set the Caller ID for a user.

8. Optional: Assign Dial Plan settings to users

Depending on your organization’s and users’ requirements, you might need to assign tenant dial plans to your users. Follow the instructions in Create and manage dial plans.

9. Assign the Teams calling interop policy

By default, all calling in Teams is set to Skype for Business without the option for users to change the setting.

For the implementation of Phone System with Calling Plans in Teams, you need to assign Teams Interop Policy that specifies calling to use Teams. The policy that meets this requirement is DisallowOverrideCallingTeamsChatTeams.

Assign the policy above to users to be enabled for Phone System with Calling Plans in Teams by using the Grant-CsTeamsInteropPolicy:

Grant-CsTeamsInteropPolicy -PolicyName tag:DisallowOverrideCallingTeamsChatTeams -Identity user\@contoso.com

Exercise - Manage interop policies

In this exercise, you’ll enable a user for calling in Teams. Although we don’t describe how to perform every action, we recommend some scenarios to try out.


  • An Office 365 tenant with appropriate licenses to enable Phone System with Calling Plans

    • We strongly recommend that you use a dedicated test tenant.

    • If you don’t have a test tenant, you can sign up for a trial tenant here: Office 365 Enterprise E5 Trial. However, Calling Plans are unfortunately not available through trial tenants.

    • Don’t run any tests in your production environment. Changing settings or policies might negatively affect all users and might affect their user experience.

  • Your PC set up for Skype for Business Online management

  • At least two endpoints and a phone

    • This can be two PCs, but you can also use the client in a browser or on your mobile phones.

    • To test PSTN calling, you need to have a phone that can call the country or region you’re testing PSTN calling for.

Suggested scenarios to test

  • Enable a user for Phone System with Calling Plans in Teams.

  • Sign in as the configured user, and review the Calls tab.

  • Call a PSTN number by using different formats (for example, dial a full E.164 number with the leading plus sign or dial a number without using the country code).

  • Test user features such as changing the number for call forwarding, transferring calls, or accessing voicemail.

Drive Value

Now that you have properly planned and implemented Phone System in your environment, you need to be sure that it’s used and provides a great user experience. Although complete details would exceed the scope of this training, we want to point out the most important areas of engagement:

  • Adoption and change management
    Users might simply start using the service when you offer it to them. Or they might not. Therefore, it’s important to execute proper adoption and change management.

  • Monitoring and driving usage
    We recommend that one of your KSIs be the number of active users, to help you measure how well Teams is being accepted as a phone client.

  • Monitoring and driving quality

The satisfaction of your users is directly related to the quality of their calls; therefore, it’s important that you monitor call quality and improve it, if necessary. To understand how to report on call quality, visit the Call Quality Dashboard training. Although these videos have been built for Skype for Business, they apply to Teams as well: http://aka.ms/sof-cqd.


We covered the following key learnings in this training:

  • What is calling in Teams?

  • How to plan for calling in Teams

  • How to configure calling in Teams

To learn more, see:

Next steps

  1. Sign-up for MyAdvisor for personalized deployment guidance.

  2. Start your Phone System deployment for Teams

  3. Send us feedback:

  • Post in the comments section at the bottom of this page.

  • Email us at AskTeams@microsoft.com.

  • To give us your feedback about Teams or share your ideas for new features, please visit UserVoice.

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