Dial by Extension

Modified on Fri, Dec 8, 2023 at 7:34 PM

Description: The purpose of this article is to guide you through the process of setting up the Dial by Extension feature of an auto attendant.

Auto attendants allow individuals to contact your organization and use a menu system to connect with the appropriate department, call queue, individual, or operator. You have the option to create these auto attendants for your organization using either the Microsoft Teams admin center or Ooma Enterprise Admin portal.

Auto attendants can direct calls, based on callers' input, to one of the following destinations:

  • Person in the organization: a person in your organization who is able to receive voice calls. This can be an online user or a user hosted on-premises using Skype for Business Server.
  • Voice app: another auto attendant or a call queue. (Choose the resource account associated with the auto attendant or call queue when choosing this destination.)
  • External phone number: any phone number.
  • Voicemail: the voice mailbox associated with a Microsoft 365 group that you specify.
  • Operator: the operator defined for the auto attendant. Defining an operator is optional. The operator can be defined as any of the other destinations in this list.


You will be prompted to choose one of these options at various stages as you set up an auto attendant. One of the available redirection choices involves using extensions instead of phone numbers. To implement this, you must enable the Dial by Extension feature.

Dial by extension is a feature that enables callers to establish connections with individuals within your organization by dialing their phone extensions. Any user, whether online or hosted on-premises through Skype for Business Server, is considered an eligible user and can be located through extension dialing.

How to Enable the Dial by Extension Feature

To activate the Dial by Extension feature of the configured auto attendant, ensure you complete all the provided parameters on the Call Flow Tab.

Do not forget to fill out the parameters on the General Info Tab as it is mandatory for auto attendant creation. 

On the Call Flow Tab, the options of the Directory Search becomes visible only upon enabling the "play menu options" feature in the Call Routing Options section.

For detailed information on configuring Auto attendants, please refer to the related article titled "How do I configure an Auto Attendant in Microsoft Teams?" accessible through this link.

Please note: selecting the "Dial by extension" option will not function unless there is specific preparation of designated extensions for users who may be recipients of redirected calls.

The following section in this user guide will provide you with detailed instructions on setting up phone extensions for users using the Microsoft 365 admin center.

How to Set Up Phone Extensions for Users

To set up Phone Extensions for Users, go to Microsoft 365 admin center. Locate and select the "Users" option in the left-hand menu of the page to expand it.

Once the content is displayed, choose the "Active Users" option.

Upon choosing this option, you will be directed to the "Active Users" page, where you can locate the table of active users.

Navigate through the table by scrolling up and down to locate the specific user to whom you want to assign an extension number for use with the Dial by Extension feature in the configured auto attendant. Once you click on the name of the chosen user, the personal card of the selected user will appear on the right-hand side of the window, positioned above the "Active Users" page.

Remain on the currently active Account Tab within the Personal Card of the selected user, and proceed to scroll down to the Contact Information section.

Next, click on the "Manage contact information" button to access and edit the information within this section of the Personal Card.

A new form will open, presenting a list of personal information parameters for the selected user. Scroll down to locate the "Office phone" parameter. It may already be prepopulated with a phone number.

Below, there is a table featuring three primary formats that you must use for entering an extension number. The third format should be employed when the "Office phone" parameter for the selected user is empty.


+<phone number>;ext=<extension>

+<phone number>x<extension>+15555555678x5678

Based on your specific scenario, select one of the provided formats and include an extension number in the "Office phone" parameter for the chosen user.

Finally, click the "Save changes" button to apply the entered information.

Please note: it can take up to 12 hours before changes are available to auto attendants and call queues.

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