Caller ID spoofing is the practice of causing the telephone network to display a number on the recipient's display that is not that of the actual originating station. The term is commonly used to describe situations in which the motivation is considered malicious by the speaker or writer.
Just as e-mail spoofing can make it appear that a message came from any e-mail address the sender chooses, Caller ID spoofing can make a call appear to have come from any phone number the caller wishes. Because of the high trust people tend to have in the Caller ID system, spoofing can call the system's value into question.
To use a typical spoofing service, customers pay in advance for a personal identification number (PIN), allowing them to make a call for a certain amount of time. To begin, customers dial the number given to them by the company and enter their PIN. Then they enter the number they wish to call and the number they wish to appear as the Caller ID. Once the customer selects these options, the call is bridged or transferred and the person on the other end receives the customer's call. Assuming Caller ID is used on the receiving end, the receiver would normally assume the call was coming from a different phone number — the spoofed number chosen by the caller — thus tricking the receiver into thinking the call was coming from a different individual or organization than the caller's. Most providers work similarly to a prepaid calling card.
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