Phone cloning is the transfer of identity between one mobile telephone and another.

Phone cloning involves placing a computer chip into the target mobile telephone, allowing the electronic serial number (ESN) of the mobile phone to be modified. The ESN is normally transmitted to the cellular company in order to ascertain whether the mobile phone user is the legitimate owner of that phone. Modifying this, as well as the phone number itself (known as the mobile identification number, or MIN) paves the way for fraudulent calls, as the target telephone is now a clone of the telephone from which the original ESN and MIN numbers were obtained.

Cloning has been shown to be successful on code division multiple access (CDMA) but rare on the Global System for Mobile communication (GSM), one of the more widely used mobile telephone communication systems[1]. However, cloning GSM phones is achieved by cloning the SIM card contained within, not necessarily any of the phone's internal data (GSM phones do not have ESN or MIN, only an IMEI number.) There are various methods used to obtain the ESN and MIN; the most common are to crack the cellular company, or eavesdrop on the cellular network. GSM SIM cards are actually copied by removing the SIM card and placing a device between the handset and the SIM card and allowing it to operate for a few days and extracting the KI, or secret code[citation needed]. This is normally done with handsets that have the option of an "extended battery" by placing the normal size battery in the handset and the Kopy Kat in the now vacant extra space. This is done by allowing the device to log the interaction between the mobile telephone switching office and the handset.

[h=Effectiveness and legislation]2[/h] Phone cloning is outlawed in the [Only registered and activated users can see links. ] , which prohibits:

knowingly using, producing, trafficking in, having control or custody of, or possessing hardware or software knowing that it has been configured to insert or modify telecommunication identifying information associated with or contained in a telecommunications instrument so that such instrument may be used to obtain telecommunications service without authorization.[2]

The effectiveness of phone cloning is limited. Every mobile phone contains a radio fingerprint in its transmission signal which remains unique to that mobile despite changes to the phone's ESN or MIN. Thus, cellular companies are often able to catch cloned phones when there are discrepancies between the fingerprint and the ESN or MIN.

[h=18 USC 1029 - Fraud and related activity in connection with access devices and many state laws also prohibit or limit cloning. Example 2011 Louisiana Laws
Revised Statutes TITLE 14 Criminal law RS 14:222.2 Cellular telephone counterfeiting
[Only registered and activated users can see links. ]