Hi,
When you buy Business Voice, you get the following features and more:
- Phone System - Standard phone features include Voice Mail, Caller ID, call menus, shared phone lines, and emergency calling.
- Domestic Calling - Calls within your country or region are free. International plans and toll-free dialing are also available.
- Audio Conferencing - Lets you host conference calls with people who don't have Teams or don't have an Internet connection.
More information here:
https://learn.microsoft.com/en-us/microsoftteams/business-voice/whats-business-voice
There is an on-going feedback request for SMS/MMS support for Microsoft Teams, you can vote on it over here:
https://microsoftteams.uservoice.com/forums/555103-public/suggestions/38034796-sms-mms-in-teams-phone-system
There are third party solutions for this though, for example:
https://www.yakchat.com/yakchat-sms-for-microsoft-teams
Best regards,
Leon