Provision Telephone Numbers in Office 365

Howdy folks!

As we proceed through the inevitable that all forms of Skype for Business will be moving towards Office 365 / Skype for Business Online. This may come in the form of a Hybrid or a fully Skype Online tenant.  More and more interest has been brewing around how Cloud PBX and PSTN calling is going to work.

To ready yourself for the provisioning of users with PSTN Calling from Office 365 I’ve created a guide on how to provision a user with a Direct Inward Dial, DID, or as we often use in Europe, DDI.

In this example I am going to enable a user to use a PSTN Calling plan and DID from Frisco, Texas – my old stomping ground in the US.  I have the licenses already applied to my tenant.  To be able to provide a user with PSTN Calling the tenant will require either a E3 with PSTN Calling add on or a E5 Licenses.  In addition the tenant will require the Dialling Plan either International, National, or both.


First things first, sign into your tenant using your global administrator account, access your Admin center.

Scroll to the bottom of the menu and select Admin then Skype for Business


You should see the dashboard which is the native splash screen.


Visit the Voice tab. This will be visible if you have voice licenses applied to your tenant.  As you can see from the image below I currently have 6 numbers assigned to the account.  3 from Dallas which are in the 469 area code and 3 from Atlanta in the 678 area code.


Before I can assign any numbers to any users we must have an emergency location attributed to the account. As you can see the one in my tenant was originally the Microsoft Bellevue location.

Because we would like to have users located anywhere within the United States, and soon to be rolling outside the US, we need to add a new location. To add a new location, under the Emergency Locations tab, press the plus sign.

A new side bar will open and location details including site name and address will be inputted. In this process, you will need to validate the address and then press save.


What is address validation?

When you are setting up PSTN calling, you will need to assign a phone number and emergency address to each of your users.

Validating an emergency address involves making sure that it is legitimate and correctly formatted for emergency authorities. Only U.S. addresses can be validated. Although it’s possible to create and save an emergency address that isn’t validated, only validated addresses can’t be associated to a user. Once an emergency address is validated and saved, it can be assigned to a user. If you need to change a saved validated emergency address, you will need to create a new one.

It is possible that a partially correct emergency address may still pass validation and will be seen in the Skype for Business admin center. For example, if you mistype the name of a city, it may still pass validation, because the combination of the misspelled name along with the other correct parts of the address are enough information to route the call to the appropriate emergency dispatch center.


Review the correct address has been added and validated.


Identify the required area codes that are required. Currently all PSTN calling is only available from the United States, this will is road mapped to other geographies.


Currently select your State, and your nearest/preferred area code.

Once you select your State and City/Area Code, select how many DDI/DID numbers you require for that area. The number is limited by the amount of Calling CALs applied to the tenant.

Agree that you’re happy with the numbers, select the numbers you would like to be added to your tenant.

This would be followed by Aquire Numbers

Verify under your Voice tab that the numbers are now provisioned on your tenant.


Assign licenses: e5 and calling

From the Users, Active Users menu find your user which PSTN Calling is going to be deployed to.

Ensure that the users who require PSTN calling apply the appropriate licenses. In this scenario I have applied an E5 license and a PSTN Domestic and International Calling license.

From the Admin, Skype for Business menu

Ensure the correct User is selected, then click the Assign Number located on the right hand side.



A side bar will load

DDI/DID number range can be selected from the drop down menu.

The E 911 location will then be searched for, this is the City which the location is listed not the customer friendly name.

Once this is applied and confirmed, press the Save button

From the voice tab validate that the assigned number and the emergency location are as expected.


That’s it, the user has now been deployed with a new DID/DDI and has the correct licensing.

Some interesting findings. Although the DDI/DID originates from the United States it seems when I call an international, British, number the presented numbers can be from a large range of locations, sometimes Sweden, sometimes other EU countries.

Hope this helps! Good luck and let me know if you need more assistance.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.