When cellphones are manufactured, they are given an IMSI (or IMEI/MEID) number among others. Short for "International Mobile Subscriber Identity," the number can be up to 15 digits long. The first three of the series of numbers represent the phone's country code, followed by the network's code. The last set of digits in the IMSI are the device's "unique subscriber number." Essentially, every phone has a unique IMSI number, assigned to the device by phone manufacturers.
Dial "* # 0 6 #" and press "Send" to have the IMSI number displayed on your phone. Although this code may not work on all phones, many devices are configured to display the number after you enter this code.
Locate your phone's status settings to locate the IMSI number. For example, on Android devices, press "Menu," "Settings," "About," "Phone" and "Status." The IMSI number will be listed under a section of the screen labelled "IMSI."
Remove your phone's battery cover and battery to locate the IMSI number. When you cannot find the number on the device itself, you are likely to locate it on the compliance panel inside the battery compartment.