The Skype for Business add-on comes with several licensing options. The add-on licensing options available to you depends on your Office 365 or Skype for Business plan. See the following topics for information, features, and options that are specific to the plan you are looking for.
- Office 365 Business Premium
- Office 365 Premium, Office 365 ProPlus, or Skype for Business Online Plan 2
- Office 365 Enterprise E1, E3, and E4
- Office 365 Enterprise E5
- Office 365 Enterprise E5 (without Audio Conferencing)
- Microsoft Teams Rooms
- GOV, EDU, and non-profit organizations
Calls to other Skype for Business and Microsoft Teams users are in most cases free, but if you want your users to be able to call regular phones, and you don't already have a service provider to make voice calls, you need to buy a Calling Plan. For more information, see Phone System and Calling Plans.
Here are the Calling Plans options:
Domestic Calling Plan: Licensed users can call out to numbers located in the country/region where they are assigned in Office 365.
Domestic and International Calling Plan: Licensed users can call out to numbers located in the country/region where their Office 365 license is assigned to the user based on the user's location, and to international numbers in 196 countries/regions.
For more information on the add-on, please review the Skype for Business Add-on Document