Mobile phones are common and is unavoidable personal communication devices. It helps the investigators to locate and track criminals in real time wrt longitude and lattitude. The voice and SMS/MMS are stored and are readily available to the investigating officers.

International Mobile Equipment Number (IMEI) is a unique number (14 decimal digits plus a check digit) given to all mobile and satellite phones. It can be displayed on the phone's screen by typing '#06#'. A stolen phone can be made nonoperational by the Service provider (by knowing the IMEI number) on getting a complaint. When a mobile equipment is blacklisted, it cannot be used with any other operator. Changing of a phone's IMEI number is possible by experts, who replace a data chip with another by micro soldering.

When a person login to the internet his identity is his IP address.