To prevent unauthorized access to your device's database, go to your carrier and ask them to block the unique number it has on record for you. Doing so will allow you to recover or locate the device, and it will also prevent it from being used by the person who stole it. However, this method can be very challenging since the carrier might not be allowed to do so legally.
You will need to enter a special code to get your mobile device's International Mobile Equipment Identity (IMEI) numbers. The first three numbers are the same for every cell phone, and the last two are the generic ones.
1) Tracking phones via tracker apps installed or by using the cloud platform of the manufactures: This will help you access your phones IMEI number, which could be helpful for blacklisting the phone and thus preventing illegal use and activities.
2) Visiting the telecom service providers: the telecom service provider will help you block your phone, once you report a lost phone case to them. These steps might have some legal complications though.
3) Calling your number: most of the cases the user might have forgotten his/her phone somewhere. Calling the number might help you get back your phone if its in hand of some good souls.
4) Filing a registered complaint: You could report a missing case to the police or cyber security team. This will be helpful and prevents you from entering into legal trouble if your lost phone is used for illegal activities. The police or cyber security team can ask telecom operators to block the IMEI and all Track IMEI for finding the location of your phone.
5) Finding phone with the help of databases: certain websites and databases store IMEI information of phones and devices that are lost and found. These websites help you track your phone and also notifies you when it becomes active after a theft.