Every Apple iPhone has a unique International Mobile Equipment Identity (IMEI) number. If you suspect that an iPhone you have in your possession was stolen, you can call the mobile phone network's customer service department and ask if the device has been listed as stolen. The mobile network providers will not, however, have information about stolen iPhones that haven't yet been reported as stolen.
Find the mobile network name displayed in the upper-left corner of the iPhone's screen; for example, Vodafone, O2 or EE.
Tap the "Settings" icon on you iPhone. Select the "General" option. Tap "About" and then scroll-down to find the iPhone's unique IMEI number.
Write down the IMEI number for easy reference when you call the mobile phone network. Call the applicable network's customer service department.
Give the customer service representative the iPhone's IMEI number. The customer service rep should be able to verify if a stolen phone report was filed for that specific IMEI number.
Hand in a stolen iPhone at your local police station. Alternatively, the mobile phone network might ask you to return the stolen device direct to them.