Apps and app settings
Battery and charging
Camera and photos
Files and storage
GPS, Bluetooth, and other connections
Insurance and extended warranty
Issues, support and device information
Language and input settings
Networks, Wifi and mobile data
Security and privacy
Software and updates
Ringtones and personalization settings
SIM cards, contacts and calling
Media and other features
Devices with SIM card slots have IMEI numbers. If your device does not have a SIM card slot, like the Wifi-only variant of the Nokia T20, then the PSN can be used to identify your device.
To find your device's Product Serial Number (PSN), head to Settings > About tablet > Model and hardware. There you can find the Product Serial Number of the device.