Enabling PSTN Calling for an Office 365 E3 User in 5 Easy Steps

I frequently encounter the situation where a company (or individual) has an Office 365 tenant with all E3 licenses but they want to enable some users for Skype for Business Online PSTN Calling (the ability to dial-out and receive calls to phone numbers in a geo-region where Skype for Business Online (SfBO) PSTN calling is currently available).

This article discusses the most basic direct way to accomplish this so that people can understand the basic process and requirements.

One of the first questions people have is whether they can  purchase a handful of E5 licenses in an “E3 tenant” (an O365 tenant that currently has nothing but E3 licensed users).  The answer is ‘Yes’ – you can purchase one or more E5 licenses and apply those licenses to one or more existing E3 users (upgrade their licenses). The PSTN Calling functionality can also be enabled by purchasing add-on licenses to the E3 license, but in most cases it is just as cost effective (or more cost effective) to use the full E5 license – this is situation I describe here.

Here are the steps to fully enable PSTN Dial-In / Dial-Out for an existing Office 365 E3 user.

1.  Purchase and Assign the Necessary Licenses

For an existing E3 licensed user, there are basically have two licensing options to enable PSTN Calling:

  1. Purchase and assign an E5 license.  Then purchase and assign a PSTN calling add-on license for the user.
  2. Purchase and assign a Cloud PBX add-on license. Then purchase and assign a PSTN calling add-on license for the user.

As you can see, the significant difference between these two options is that the E5 license includes the Cloud PBX license which provides the ability to then purchase a PSTN calling plan so that the user can make and receive phone calls in regions that have PSTN Calling enabled (in May 2017 this includes the US, France, UK, Spain, and Puerto Rico). The E3 license does not contain the Cloud PBX add-on license, and you must separately purchase it.

Tip – think of the Cloud PBX license as providing PBX-like call control capabilities, but not the PSTN calling plan (or connectivity) on-top. The PSTN Calling Plans and Cloud PBX licenses go together – the Cloud BPX license is required to have the ability to add a voice calling plan.

The cost of an E3 license with the Cloud PBX add-on in USD as of May 2017 is:

  • Office 365 E3: $20 / user / month
  • Skype for Business Cloud PBX :  $8.00 / user / month
  • TOTAL:  $28 / user / month

The cost of an E5 license as of May 2017 is $35 / user / month (USD) which also includes PSTN Conferencing capabilities, MyAnalytics, Advanced Treat Protection, Advanced Information Protection (DLP and encryption), and more features, so it is worth considering for the extra $7 / user / month.

FYI, as of May 2017, the Skype for Business PSTN Domestic Calling add-on license in the US is $12.00 / user / month.

Once you have purchased an E5 license (or the equivalent add-on Cloud PBX and PSTN Calling licenses for E3), go into the Office 365 Admin Portal and assign the E5 license to a user.  This is straightforward process (see here if you have any questions: Assign or remove licenses for Office 365 for business).

Tip – you need to turn off the existing E3 or E1 license before assigning the E5 license or the Office 365 Admin Portal will give you an error about “conflicting plans” – e.g.  Skype for Business Online Plan 1 conflicting with Skype for Business Online Plan 2.

After assigning the E5 license, it is normal to see this warning:


In fact, before we can assign the user a phone number, you need to ensure the user has a PSTN Calling Add-On License as described in Step #3.

Tip – in my experience there is always a delay, and it’s not just a fSkype for Business PSTN Domestic Calling ew minutes.  I’ve typically had to wait many hours. In fact, as stated in the Microsoft Support Article  Assign Skype for Business licenses :

Latency after assigning licenses: Because of the latency between Office 365 and Skype for Business Online, it can possibly take up to 24 hours for a user to be enabled for PSTN Calling after you assign a license. If after 24 hours, the user isn’t enabled for PSTN Calling please call us.

2. Acquire and Assign a Skype for Business Online PSTN Calling Add-On License

The ability for a user to make and receive calls through the phone system is an add-on license on top of the E5 license.  You can purchase this option through the “Billing | Purchase Services” options in the O365 Admin Portal.  There are a couple of options for PSTN Calling based on your region as shown below for the United States:


For all the various PSTN Calling add-on license plans see PSTN Calling plans for Skype for Business.

Tip – If you haven’t assigned a CloudPBX or PSTN Calling add-on License to a user, you will see this in the Voice tab of the SfBO Admin Portal


Once you have obtained a PSTN Calling Add-On License (or CloudPBX license), you should see it in the available licenses in the Office 365 Admin Portal when  you edit a user (under Active Users) to apply it as shown here:


Once the add-on license is successfully applied to a user and the change replicates to SfBO, you will see the user enabled for Voice in the SfBO Admin Portal as shown here:


Tip – many times I need to re-launch the SfBO Admin portal from the O365 Admin portal to see this change.  You might get the same result by refreshing the browser.

Now that a user is licensed for E5 and PSTN calling, you just need to configure an emergency location, and acquire and assign the user a phone number.

Step 3.  Configure an Emergency Location for the User

A this point, if you try to assign the a phone number to the user, you will quickly find out that you need to add an Emergency Location for the user before you can assign a number as shown here with this warning:


This location represents a real physical address where the user consuming PSTN will likely reside and is used in the case the user dials an emergency number (e.g. “911” in North America).

Configuring Emergency Locations is a straightforward process you can configure under in the “emergency locations” in the SfBO voice settings.  A real example is shown here:


Tip – this needs to be a real physical address and it is validated against a database of real addresses before you can save and continue.

Step 4.  Acquire a Phone Number

Before you can assign a phone number to a user, you need to acquire one. You can do that in the SfBO Admin Portal under “voice” and “phone numbers” and select the “+” sign the Add a New Number. You will be able to select a new DID from the regions where PSTN calling is supported for the location of your Office 365 tenant as shown here:


You should see the newly acquired DID in the available phone number list.

Step 5.  Assign a Phone Number

After successfully configuring an Emergency Location for the user, and acquiring a phone number, we can now assign a phone number to a user.  Go into “Voice | Voice Users” in the SfBO portal as shown here:


And finally, after selecting the previously acquired phone number and emergency location, you can enable this user for PSTN Calling!


Tip – all of the above steps showed how to do this in the Office 365 and SfBO Admin Portal but it can all be accomplished through PowerShell (e.g. for configuring many users).

More Information

The following Microsoft articles provide more information on PSTN Calling:

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