Microsoft Teams Extension Dialing Steps

Several years ago I wrote a blog about how to setup Extension Dialing for Skype for Business Online. It turned out to be one of my most popular blogs (of the almost 100 blogs I have written over the years) to date, indicating to me just how many people were interested in this feature. I have had several requests to create a similar blog about how to setup extension dialing in Microsoft Teams, so here it is!

First of all, what is Extension Dialing and why would an organization need to set this up. Extension Dialing has been around for decades and is a way for people in an organization to reach one another by phone by simply entering a three or four digit extension (you can make it however many digits you need). So imagine an organization that has existed for 30 years with this capability and you are working there. You would easily remember that John was at extension 101, that Rebecca was at extension 302 in another building, or that your manager Laurie is at extension 130. You, the people mentioned above, and so many others have all worked at this organization for 10, 20, or even more years. You have these extensions memorized just like your home address. And now, this organization wants to modernize how they collaborate.

Continuing on with our example, the modernization plan at the organization includes deploying Microsoft Teams, Microsoft Meetings, and Microsoft Calling services. The plan is to migrate off of the existing PBX providing calling services and over to Microsoft Teams. As part of the plan, it cannot cause any business interruptions. This includes how people communicate today using extension dialing. Instant Messaging with Microsoft Teams will eventually become the norm for communications, but for now extension dialing is a must. So let’s get into how this is implemented using Microsoft Teams.

A few notes:

• While you enable the extension dialing for each user, it may take up to 12 hours for Azure Active Directory Phone Numbers and Mobile Phone users are synchronized.
• You must use the Microsoft 365 Admin Center for this setting, NOT the Microsoft Teams Administration Center(TAC)
• Follow the instructions below. Do not use the user LineURI to define extension dialing.
• There are two different methods to set this up. One if you are using only Azure Active Directory and a second if you are syncing between Active Directory on-prem and Azure Active Directory in the cloud. This method only describes Azure Active Directory users. If syncing with on-prem Active Directory, you will need to use ADSI Edit or Active Directory Users and Computers to edit the Telephone Attribute field.
• More information is available in this link from Microsoft (see the Directory Search section.

Steps using Microsoft 365 Administration Console:

In this example, we are going to setup two users for extension dialing. These are fictional users in a lab environment.

• Debra Burger has telephone number xxx-803-3416 and has had extension 3416 for years
  • We want to use a format of “phonenumber;ext=(extension)” or “x(extension)” so in this lab environment we are going to specify +1xxx8033416;ext=3416
• Nestor Wilke has telephone number xxx-803-3405 and has had extension 3405 for years

1. Open the Microsoft 365 Administration Console at portal.office.com.
2. Expand Users, and then select Active Users
3. Locate the user in our example Debra Burger

4. Click on Debra’s name to open the side panel. From here, scroll to the bottom where the Contact Information is located. Click on Manage Contact Information.

5. Under Manage Contact Information, remove the Office Phone number and replace it with your telephone number and extension using a format of “phonenumber;ext=(extension)” or “x(extension)”. In this example, we’ll use

+1(area code)8033405;ext=3405

6. Click Save Changes
7. Repeat the same steps for additional users.
8. Like I mentioned in the notes above, it may take up to 12 hours for the extension dialing to work for this user.

Extension Dialing Settings Using PowerShell:

You may want to use PowerShell to enable extension dialing, especially if you have a large number of users to setup with this functionality. For more information about how to create a CSV file with multiple users, please see this link. This method is definitely the way to go when editing/adding hundreds or thousands of users for extension dialing. Once the CSV and PowerShell command is ready, it takes seconds to complete.

1. To access the Microsoft Teams Powershell commands, please see this separate blog I wrote on the topic with step-by-step instructions.
2. When connected to your Microsoft 365 tenant and you have the Microsoft Teams modules imported, you can now enter the command to set the extension for your user. In my lab, I am again going to use Debra Berger as our user. This is the PowerShell command I used:

Set-MsolUser -UserPrincipalName debra.berger@kmartins2.com -Phonenumber +1(area code)8033416;ext=3416

3. Repeat the same steps for additional users.
4. Like I mentioned in the notes above, it may take up to 12 hours for the extension dialing to work for this user.

If you have any questions or comments, be sure to leave them below.