Dial by extension in Microsoft Teams is question that comes up frequently. If you’ve created an Auto Attendant in the Teams Admin Centre, you’ve probably noticed the dial by extension option under Directory Search. At this point you would be forgiven for thinking enabling Teams dial by extension was simply a case of selecting the radio button and away you go. Unfortunately enabling the feature isn’t quite that straight forward, even if you have a LineURI specified against a user account in Teams, this isn’t where the extension itself is derived from.
In order for dial by extension for users to work, their telephone and extension number needs to be populated against their Active Directory user account. This needs to be in a specific format in order for the telephone number and extension to be identified by Teams. Microsoft state the following formats are supported, this is buried away in their official documentation:
“phonenumber;ext=(extension)” or “x(extension)”
Our recommendation is to use the “phonenumber;ext=(extension)” method, this format would mean the users number would would be for example +44203456789;ext=789. This example does however assume the last three digits of the DDI match the extension, however it is perfectly fine for the two numbers to differ. If you have on-premise Active Directory synchronising via Azure AD Connect, you can simply populate the number and extension in the Telephone Number field as shown below.
If you only use Azure AD you can either use Set-AzureADUser or Set-MsolUser via a PowerShell session. We prefer Set-MsolUser as you can specify the user principle name as opposed to an object ID. You can run the following command MsolUser command.
Set-MsolUser -UserPrincipalName firstname.lastname@example.org -Phonenumber +44203456789;ext=789
Once the change has been applied it can take up to twelve hours for this to completely replicate in Office 365. Once replication has occurred, you will now be able to call your Auto Attendant and dial an extension followed by # to be connected to the end user. That’s it, we hope you’ve found our Teams dial by extension article helpful. If you need any further assistance, then please feel free to use the contact form below or check out our support services.