Applies To

Call2Teams - Customers


The service relies on a high degree of automation. 

This is used in order to provision into Office 365, and to manage the service with the Sync Now feature.

An issue with a missing API in the customer's Azure Tenant can lead to a problem provisioning the service. Attempting to perform a first Sync returns an Invalid_Client error.

The process below outlines the test a customer can perform to verify the presence of the Application Programming Interfaces (APIs) required in their Office 365 tenant. 


Where the API is not found, then Microsoft should be notified as this demonstrates a provisioning issue with the build of the customer's Office 365 tenant, Microsoft needs to resolve this. 

Follow the steps below to try and restore the missing API:

Verify the API

1. Log in to the customer's Microsoft 365 admin center using credentials with Global Admin privileges: 

2. In the admin center, click Show All on the menu.

3. Open Azure Active Directory under Admin Centers.

4. In the Active Directory Admin Center click on Azure Active Directory.

5. In the Overview menu click on App Registrations.

6. Click New Registration

7. Enter a name for the app - the name itself is not important.

8. Under the options, select Accounts in any organizational directory (Any Azure AD directory - Multitenant).

9. Click Register.

10. In the newly created app, select API Permissions.

11. Select Add a Permission.

12. Under Select an API, click on APIs my organization uses.

13. Enter the following GUID into the search box: 39624784-6cbe-4a60-afbe-9f46d10fdb27

If the search returns 'No Results' then the API is absent in from the Microsoft tenant.

If the search returns Teams and Skype for Business Administration then the API is present:

Using PowerShell to Install The Missing API

Follow these steps to fix the Microsoft tenant so the service can be deployed:

Install the Azure PowerShell module

Follow the instructions below - these instructions can also be found at

1. On a Windows PC, Run PowerShell as administrator

2. PowerShell will now launch in Administrator mode

3. Run the following command: 

Install-Module -Name Az -AllowClobber  

PowerShell will take a few moments to install some dependent modules. Approve the installation requests that appear during the process:

4. Run the following command to login:


5. Run the following command to install the API endpoints to the tenant:

New-AzADServicePrincipal -ApplicationId "39624784-6cbe-4a60-afbe-9f46d10fdb27"

Note: If this generates an error then run this command:

set-executionpolicy remotesigned

The following should be returned from PowerShell and resolve the issue:

6. Proceed with the Sync process.


Please note Destiny Automate Ltd. (formerly Qunifi Limited) cannot be held responsible for the content of any third-party documentation offered.