To enable SMS in Microsoft Teams you will require a specific type of Microsoft Teams license. Every active user must have one of the following license types:
- Teams Phone Standard (Default License)
- Microsoft and Office 365 Enterprise E5
- Microsoft 365 and Office 365 Education A5
- Microsoft 365 and Office 365 Government G5
- Microsoft 365 and Office 365 Nonprofit E5.
To purchase the license navigate to your Organization Portal and click on Marketplace.
Search for Microsoft Teams Phone Standard and click on Details
Select your license count
Assign Microsoft Teams Phone Standard Licenses to your users
For a full breakdown of the difference between licenses please refer to Microsoft Documentation.