Dear Tarun Arora_84
Greetings!
Thank you for posting on Microsoft Community!
Based on your description, I understand your issue with incoming call is not visible on MS Teams mobile which is a Xiaomi device.
It seems you've checked App Permissions, Notification permissions, Battery optimization settings yourself but it's not visible. In this case, it's suggested to firstly uninstall and then reinstall Team on your phone from Play Store. Download Microsoft Teams Desktop and Mobile Apps | Microsoft Teams
Moreover, please note that Microsoft Teams integrates with Mi push directly to optimize the push notification experience in Xiaomi devices, but it needs some specific configuration setup in Xiaomi phone to turn on the Mi push. Please kindly refer to this article to learn how to set up the configuration in Xiaomi phones and about the known limitation you may experience.
Appreciate your patience and understanding and thank you for your time and cooperation. I wish you all the best!