Issues receiving messages and calls on legacy systems
Users might have issues receiving messages or calls if they're using older versions of Teams or have logged in with other applications.
If users are signed in to a domain-joined computer and you don't want their user name pre-populated on the Teams sign-in screen, admins can set the following Windows registry to turn off prepopulation of the user name (UPN):
Computer\HKEY_CURRENT_USER\Software\Microsoft\Office\Teams
SkipUpnPrefill(REG_DWORD)
0x00000001 (1)
Note
Skipping or ignoring user name pre-fill for user names that end in ".local" or ".corp" is on by default, so you don't need to set a registry key to turn these off.
See Sign in to Microsoft Teams using modern authentication for more information.
When changing/resetting a password, older clients won't receive messages and calls for up to an hour. To resolve this issue, either restart the app or move to newer clients.