Context
Calls made on the Teams app on an iOS device drop immediately
Details
Review the following settings and adjust as necessary
1. Navigate to Settings > scroll down to Teams
Local Network (make sure this is enabled)
Microphone (make sure this is enabled)
Background App Refresh (make sure this is enabled)
Cellular Data (make sure this is enabled)
Note: The settings should enabled by default unless denied during setup or later disabled. However, if you have recently installed the Teams app the installer has changed and they may not all be on by default any longer.
2. Reboot the iOS Device and make a test outgoing call.