Hi @mohamed sameen
Can you log in to Teams normally on the web client and desktop client?
If Teams can log in normally on the web client and desktop client, please try to uninstall the mobile client Teams and reinstall it.
If the VPN is active during the issue. If it is try deactivating the VPN to see if the issue persists.
If you're using cellular, try switching to wifi and vice-versa.
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