Caller Identification, or "Caller ID," allows you to identify a caller before you answer your telephone. A caller's number and/or name are displayed - on your phone or an external display unit. Some phone and cable companies offer widgets that allow you to see caller ID displayed on your TV or computer screen.
Caller ID service, however, is susceptible to fraud. Using a practice known as "caller ID spoofing," callers can deliberately falsify the telephone number and/or name relayed as the Caller ID information to disguise the identity of the calling party.
FCC rules on caller ID spoofing
Under the Truth in Caller ID Act, FCC rules:
- Prohibit any person or entity from transmitting misleading or inaccurate caller ID information with the intent to defraud, cause harm, or wrongfully obtain anything of value.
- Subject violators to a penalty of up to $10,000 for each violation of the rules.
- Exempt authorized activities by law enforcement agencies and situations where courts have authorized caller ID manipulation to occur.
What are the rules regarding caller ID for telemarketers?
FCC rules specifically require that a telemarketer:
- Transmit or display its telephone number or the telephone number of the seller on whose behalf the telemarketer is calling, and, if possible, its name or the name and telephone number of the company for which it is selling products or services.
- Display a telephone number that you can call during regular business hours to ask to no longer be called. This rule applies even to companies that already have an established business relationship with you.
What other tips can the FCC give consumers?
- Don't give out personal information in response to an incoming call. Identity thieves are clever – they often pose as representatives of banks, credit card companies, creditors, or government agencies to get people to reveal their account numbers, Social Security numbers, mother's maiden names, passwords and other identifying information.
- If you get an inquiry from a company or government agency seeking personal information, don't provide it. Instead, hang up and call the phone number on your account statement, in the phone book or on the company's or government agency's website to find out if the entity that supposedly called you actually needs the requested information from you.
What are the rules for blocking and unblocking your telephone number?
The FCC's Caller ID rules protect the privacy of the person calling by requiring telephone companies to make available free, simple and uniform per-line blocking and unblocking procedures. These rules give you the choice of delivering or blocking your telephone number for any interstate (between states) call you make. (The FCC does not regulate blocking and unblocking of intrastate calls.)
- To block your telephone number for any call, dial *67before dialing the telephone number.
- To unblock your number for any call (if you have a blocked line), dial *82 before dialing the telephone number.
What can I do if I suspect a violation of caller ID rules?
If you have caller ID and receive a call from a telemarketer without the required caller ID information, if you suspect that Caller ID information has been falsified, or you think the rules for protecting the privacy of your telephone number have been violated, you can file a complaint with the FCC.
Filing a complaint
You have multiple options for filing a complaint with the FCC:
- File a complaint online 
- By phone: 1-888-CALL-FCC (1-888-225-5322); TTY: 1-888-TELL-FCC (1-888-835-5322)
- By mail (please include include your name, address, contact information and as much detail about your complaint as possible):
Federal Communications Commission
Consumer and Governmental Affairs Bureau
Consumer Inquiries and Complaints Division
445 12th Street, S.W.
Washington, DC 20554
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Caller ID and Spoofing Guide  (pdf)