Report the phone as lost or stolen to your mobile carrier
Provide the IMEI number to your carrier
Ask the carrier to block the device using the IMEI
File a police report and include the IMEI number
Contact the phone manufacturer for device tracking or support options
Use Find My Device on Android if it was previously enabled
Use Find My on iPhone if it was previously enabled
Log in to your Google or Apple account from another device
Check the last known location if available
Change passwords for important accounts linked to the phone
Remove payment methods and sign out of accounts remotely
Monitor the IMEI with any stolen phone tracking services if available
Keep the IMEI number for future identification if the phone is recovered