Configure and Manage a Teams Environment
Tenant-wide plumbing
Teams administration spans several consoles, and MS-700 questions test whether you know which one owns a setting. Guest access (letting external users join teams as guest accounts via Entra B2B) and external access (federation for chats and calls with other domains) are independent switches in Teams admin center; enabling one never enables the other. Team creation is not a Teams policy at all, it is the Microsoft 365 Groups setting in the Microsoft 365 admin center.
Upgrade and coexistence
Moving from Skype for Business relies on coexistence modes: Islands, Skype for Business Only, Skype for Business (default), and Teams Only. Assign modes per user or tenant-wide; Teams Only users meet only in Teams, and the Meeting Migration Service converts existing Skype meetings. A user must be upgraded before Skype-only features disappear for them.
Policies and precedence
Messaging, meeting, calling, app, and live event policies are assigned directly to users, via group assignment, or fall through to the org-wide default. A direct assignment always wins. When a user belongs to multiple groups, the most restrictive policy wins. Policy packages bundle role-based defaults such as Frontline Worker or Education.
Network readiness
Use Network Planner to size bandwidth per site, then apply QoS with DSCP tagging. Media should bypass proxies and VPN hairpins and use the required UDP ports.
Worked example. A helpdesk reports users cannot create new teams. Reviewing messaging and meeting policies finds nothing, because creation is governed by the Microsoft 365 Groups setting in the Microsoft 365 admin center. Fix it there (or with Entra PowerShell), not in Teams admin center.