By default Microsoft Skype for Business will be preferred application to receive incoming voice call. We can set it to Microsoft Teams by using powershell.
1. Click Start, click All Programs, click Accessories, click Windows PowerShell, and then click Windows PowerShell.
After the Windows PowerShell console appears, you must then create a Windows PowerShell credentials object. The credentials object is used to securely convey your user name and password to Skype for Business Online. To create a credentials object, type the following command at the Windows PowerShell prompt and then press ENTER:
$credential = Get-Credential
After you press ENTER, you should see the Windows PowerShell Credential dialog box. In the User name box, type your Skype for Business Online user name. In the Password box, type your Skype for Business Online password.
if you want to verify that the object was created, simply type the variable name at the Windows PowerShell prompt and press ENTER:
2. Next you need to import SkypeOnlineConnector module. To do that run the followign commands:
3. After you have created the credentials object, you can then create a new remote Windows PowerShell session that makes a connection to Skype for Business Online. To do this, type the following command at the Windows PowerShell prompt and then press ENTER:
$session = New-CsOnlineSession -Credential $credential -Verbose
If your connection succeeds, you’ll see messages similar to this in the Windows PowerShell console:
4. The New-CsOnlineSession cmdlet connects to Skype for Business Online and creates a new session for you. However, you must then import that new session into the Windows PowerShell console. Do this by running the following command:
At this point, you are ready to begin using Windows PowerShell to manage Skype for Business Online.
5. Next, incoming voice calls need to be routed to the Teams client. This is controlled via a Teams interop policy that is assigned to each user. This allows a controlled, staggered approach to rolling out PSTN calling to users to avoid potential interruptions. Here are the Teams interop policies available in my tenant:
The default application for CallingDefaultClient & ChatDefaultClient is Default; which mean Skype for Business.
6. Run the following command to change it to Teams and verify it
Grant-CsTeamsInteropPolicy -PolicyName tag:DisallowOverrideCallingTeamsChatTeams
7. Once we assigned the interop policy, the Teams client needs to be configured as the default calling application. If you click on your user icon in the bottom left, then Settings, then Calls, you will have several options for controlling your calling experience, such as simultaneous ringing, changing voicemail greeting, and setting the default application for incoming calls:
Now Microsoft Teams will be the default application for all incoming call.