Microsoft 365 Business Voice is a phone system which has been designed to integrate with Office 365. It is an add-on for Microsoft Teams that gives you the ability to make phone calls in the Teams desktop or mobile app.
It is a reliable and secure service using Microsoft’s cloud which adds flexibility to your meetings with a dial-in number. You can also get new phone numbers to use or migrate existing ones to the system.
More information can be found on Microsoft’s website here > https://www.microsoft.com/en-gb/microsoft-365/business-voice