Caller ID spoofing is a violation of federal law in the United States, with the exception of law enforcement applications. Blocking caller ID information entirely is a legal way to prevent call recipients from receiving a caller's personal information.
Law enforcement activities that spoof caller ID must be specifically authorized. Spoofing can also be authorized by a court hearing. If spoofing is done with the intent to defraud, deceive, or obtain any item or information of value, the violation is subject to monetary penalties. These laws include calls placed over VOIP or other digital telephone protocols.
The FCC requires telephone companies to provide free caller ID blocking services to customers. Dialing *67 before placing a call blocks a line from appearing on caller ID, regardless of which telephone company carries the call. Dialing *82 before placing a call from a blocked line removes the block and allows the customer's information to appear on caller ID again. The FCC advises consumers to use this free service when privacy is necessary.
Special rules apply to telemarketers. Caller ID blocking is illegal for telemarketers, and the number displayed on caller ID must accept calls during business hours. Customers who call this number and opt out of future communications must have their requests honored.