Move some users to "Teams Only" mode with powershell

This is a simple script that reads sip address from a csv file and change mode.

$Users = Import-Csv -Path c:\temp\users.csv

foreach($User in $Users)
{

Grant-CsTeamsUpgradePolicy -Identity $User.SipAddress -PolicyName UpgradeToTeams

}

If you want to change for all users in your organisation you can change the default mode instead. Teams Admin Center > Org-wide Settings > Teams Upgrade, change Coexistence mode to Teams only.