Find my Phone or similar is the name given by various manufacturers to software and a service for smartphones, whereby a registered user can find the approximate location of the phone if switched on, over the Internet, or by the phone sending e-mail or SMS text messages. This helps to locate lost or stolen phones Apple offers a free service called Find My iPhone for iPhones running iOS. Microsoft’s My Windows Phone offers a similar service for phones running Windows Phone. Similarly, Google offers Find My Device for phones running Android
Some of these applications may have limitations which can be checked before installing, such as only working in some countries, dependencies upon the phone’s implementation of GPS, etc. Similar paid or free apps are also available for all device platforms.
Similar applications are available for computers. Computers rarely have built-in GPS receivers or mobile telephone network connectivity, so these methods of location and signalling are not available. A computer connected to the Internet by a cabled connection gives its location as the location of the Internet Service Provider (ISP) it is connected to, usually a long distance away and not very useful, although the IP address may help. However, a WiFi-connected computer (typically a laptop computer) can find its approximate location by checking WiFi networks in range against a database, allowing approximate location to be determined and signalled over the Internet
GSM networks use the IMEI number to identify valid devices, and can stop a stolen phone from accessing the network. For example, if a mobile phone is stolen, the owner can have their network provider use the IMEI number to blacklist the phone. This renders the phone useless on that network and sometimes other networks, even if the thief changes the phone’s subscriber identity module (SIM).
The IMEI only identifies the device and has no particular relationship to the subscriber. The phone identifies the subscriber by transmitting the International mobile subscriber identity (IMSI) number, which it stores on a SIM card that can, in theory, be transferred to any handset. However, the network’s ability to know a subscriber’s current, individual device enables many network and security features.