Note: Phone App is available as an additional 'add-on' to existing PBX or Trunk services. If the options 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. 


The Phone App is a lightweight calling experience for Microsoft Teams users to make and receive phone calls from a Teams App that is automatically loaded into the users Teams environment as a part of the service. 

Being a separate App to the native Teams calling experience, 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 PBX capabilities provided by their existing phone service to deliver the feature set that a business user would expect.

The Phone App users can be mixed in the same customer organisation that is using the Microsoft Phone System 'Standard User' experience so the customer can choose the 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 thier name in Teams. 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 available here

Configuring Phone App

The Phone App capability is enabled in the Teams services tab. An additional setting 'Phone App Only' enables a quicker setup process for accounts where there are no Standard Teams users, only Phone App users.

Save the configuration after enabling Phone App and then run a Sync Now process,

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

  1. In the left navigation, go to Org-wide settings > 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 the with the organization, skip to step 5.

  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 domain

    • 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 to be in a "Teams Only" mode. This may already be the case but to check this setting please follow the Steps in the Screenshot below;

If you have had to Upgrade from Islands to Teams Only Mode you will also need to follow the steps in this KB to upgrade within our platform;Upgrade from ISlands to Teams

For more information around 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 user from the list  and configure SIP credentials or Trunk numbers as for a Standard user.