Final answer:
Cloning is the process of duplicating the Electronic Serial Number (ESN) of a phone to make fraudulent calls charged to the original phone's owner.
Step-by-step explanation:
Duplicating the Electronic Serial Number (ESN) of one phone and using it in a second phone is called cloning. This fraudulent activity allows the perpetrator to have calls and other transactions billed to the original phone owner's account. In the process of phone cloning, the perpetrator copies the ESN of a legitimate mobile phone and reprograms another phone with the same ESN. This makes the second phone a duplicate of the original, enabling the culprit to make calls at the expense of the victim without being easily detected.