License requirements for Direct Routing are straightforward:  You must have your own Microsoft Teams account and license.  An Office 365 E1, E3, or E5 license required.  Virtual phone numbers must be purchased through AVOXI and routed through SIP to Microsoft Teams.  An AVOXI license is not required to configure Direct Routing for your Microsoft Teams environment. If you have not set up your Microsoft phone system yet, the following will help you figure out what you still need to get started.