Applies To

Call2Teams - Customers

Phone App is available as an add-on to existing PBX services. If the option is not available in the portal then the service has not been provisioned to the account and needs to be enabled via the licensing provider. 

Phone App is currently only available to Call2Teams for PBX users.


Phone App is an add-on to the Call2Teams PBX license that embeds a dialler in Teams for native calling.

The Phone App is automatically loaded into the users Teams environment as a part of the service. 

There are some limitations to the user experience compared to the full Microsoft ‘Phone System’ calling experience. 

Since the Phone App does not enable any of Microsoft Teams’ native phone system capabilities (e.g. auto attendant, call queues etc.), customers/users should rely on the PBX capabilities provided by their existing phone service to deliver the feature set that a business user would expect.

Phone App users can exist in the same customer organisation as a Microsoft Phone System 'Standard User', so the customer can choose which capability to assign users as required.

Note: For a user to operate with the Phone App service they must be in Teams only mode. If they are in Skype for Business mode, the Skype 'S' symbol will appear by their name in Teams when being contacted from another organization. If this is showing then the user will not work with Phone App.

Refer to Microsoft documentation for moving users between Skype for Business and Teams modes here

Note: Microsoft are changing the name of the Phone System Licence to Teams Phone Licence. Please be aware that references to both may continue to co-exist for a time. 

License Requirement for Phone App

Phone App Requires a standard PBX user SKU and a Phone App user SKU. For each configured Phone App user in the portal they will use one of each licences. 

Configuring Phone App

The Phone App capability is enabled in the Teams services tab.

Save the configuration after enabling Phone App and Authorize Phone App for my Organization then run a Sync Now process.

Syncing Phone App Users

The previous step will need to be completed before Phone App only users can be Synchronized in. 

A Sync will need to be performed before and after adding/configuring the users.

Note: If the customer is using Large Tenant Mode then they will need to define an Azure AD Group for Phone App users. 

                        Phone App users cannot be part of the standard Azure AD groups.

Configuring Microsoft 365 to work with Phone App

Phone App relies upon the service global network to place calls directly to Microsoft Teams users through a method referred to as ‘external access’.  

External access is managed within the Teams admin center, and a function of this management is to enable calls from the domain used by the service for Phone App.

Microsoft tenants have this capability fully enabled by default but if external access has been restricted then this is managed in the Teams admin center:  

Using the Microsoft Teams Admin Center

Go to

  1. In the left navigation, go to Users > External access.

  2. Turn on the Users can communicate with other Skype for Business and Teams users setting to enable External Access.

    Screenshot of Users can communicate with other Skype for Business and Teams users setting turned on.

  3. If all Teams external organizations are to communicate with the organization, skip the next step; the Microsoft tenant is ready for external access.

  4. If a limit to the organizations that can communicate with users in the organization is needed,  either allow all except some domains, or allow only specific domains.

    • To limit communications to specific organizations, add those domains to the list with a status of Allowed. Once these are added any domain to the Allow list, communications with other organizations will be limited to only those organizations whose domains are in the Allow list.
    • Be sure to add the Phone App domain ( ) to the Allow list.
    • Click Save.

Phone App also relies on the Microsoft 365 Tenant or User to be in "Teams Only" mode. Depending upon organization requirements, it may be easier to move the entire Microsoft 365 tenant to Teams Only mode, or this can change can be made to an individual user. 

To check this setting please follow the steps as shown in the screenshot below:

  1. Navigate to Teams upgrade settings
  2. Under Coexistence mode select Teams only
  3. Click Save

Customers who upgrade from Islands to Teams Only Mode will also need to follow the steps in this knowledgebase article to upgrade within the platform:

 Islands Mode/Teams Only Mode

NOTE: if the Microsoft portal reports the error "We can't upgrade this organization to Teams Only mode" then review this article for temporarily removing domains to complete this process: Islands Mode moving to Teams Only mode

 Upgrade a Single User to Teams Only

For a small number of Phone App users within the 365 Tenant then it may be easier to set them users to Teams Only Mode. Follow these steps:

 Using the Microsoft Teams admin center

  1. In the left navigation, go to Users, and then select the user to modify from the list
  2. On the Account tab for the user, under Teams upgrade, click Edit
  3. Set the Coexistence mode to Teams Only
  4. Click Save

For more information on Teams Only Mode please see;

Configuring Phone App users

When Phone App is enabled, all users from a connected Microsoft 365 account will be configurable in the Users tab of the portal. The Phone App users will have a different icon identifying them as Phone App users and not Standard users:

Phone App User
Standard User

Select the Phone App user from the list and configure their SIP credentials as for a Standard user.


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