Microsoft 365 Domestic Calling Plan - subscription license - 120 minutes

Calls to other Skype for Business and Microsoft Teams users are 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. With Domestic Calling Plan licensed users can call out to numbers located in the country/region where they are assigned in Office 365.