Caller ID spoofing

Caller ID spoofing
Example of Caller ID spoofed via Orange Boxing, both the name and number are faked to reference "leetspeak".

Caller ID spoofing is the practice of causing the telephone network to display a number on the recipient's Caller ID 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.

The above method is a bit complex; many Caller ID spoofing service providers also allow customers to initiate spoofed calls from a Web-based interface. Some providers allow entering the name to display along with the spoofed Caller ID number, but in most parts of the United States, for example, whatever name the local phone company has associated with the spoofed Caller ID number is the name that shows up on the Caller ID display. In other words, the name is not derived from the phone network; instead the originating number is looked up in a database, often over the Internet, and that name is used instead.

Using a Web-based spoofing service involves creating an account with a provider, logging in to their Website and completing a form. Most companies require the following basic fields:

  1. source number
  2. destination number
  3. Caller ID number

When the user completes this form and clicks a button to initiate the call, the source number is first called. When the source number line is answered, the destination is then called and bridged together.

Some providers also offer the ability to record calls, change the voice and send text messages.

Other popular methods by companies include displaying only a geographic name on the caller ID readout, e.g., "ARIZONA", "CALIFORNIA", "OREGON", or "ONTARIO".

Technology and methods

Caller ID is spoofed through a variety of methods and different technology. The most popular ways of spoofing Caller ID are through the use of VoIP or PRI lines.

Another method of spoofing is that of emulating the Bell 202 FSK signal. This method, informally called orange boxing, uses software that generates the audio signal which is then coupled to the telephone line during the call. The object is to deceive the called party into thinking that there is an incoming call waiting call from the spoofed number, when in fact there is no new incoming call. This technique often also involves an accomplice who may provide a secondary voice to complete the illusion of a call-waiting call. Because the orange box cannot truly spoof incoming caller ID prior to answer and relies to a certain extent on the guile of the caller, it is considered as much a social engineering technique as a technical hack.

Other methods include switch access to the Signaling System 7 network and social engineering telephone company operators, who place calls for you from the desired phone number.

In the past, Caller ID spoofing required an advanced knowledge of telephony equipment that could be quite expensive. However, with open source software (such as Asterisk or FreeSWITCH, and almost any VoIP company), one can spoof calls with minimal costs and effort.

Legislation in the United States

On April 6, 2006, Congressmen Eliot Engel (D-NY) and Joe Barton (R-TX) introduced H.R. 5126, a bill that would have made caller ID spoofing a crime. Dubbed the "Truth in Caller ID Act of 2007", the bill would have outlawed causing "any caller identification service to transmit misleading or inaccurate caller identification information" via "any telecommunications service or IP-enabled voice service." Law enforcement was exempted from the rule. Three weeks later, an identical bill was introduced in the Senate. [1] On June 6, 2006, the House of Representatives passed the Truth in Caller ID Act, although no Senate action was taken on either the House or Senate bill. At the end of the 109th Congress, the bill expired (all pending legislation not voted into law at the end of the House term, a.k.a. end of a session of Congress, is dead).

On January 5, 2007, Congressman Engel introduced H.R. 251, and Senator Bill Nelson (D-FL) introduced a similar bill (S.704) two months later. On June 27, 2007, the United States Senate Committee on Commerce, Science and Transportation approved and submitted to the Senate calendar S.704, a bill that would have made caller ID spoofing a crime. Dubbed the "Truth in Caller ID Act of 2007", the bill would have outlawed causing "any caller identification service to transmit misleading or inaccurate caller identification information" via "any telecommunications service or IP-enabled voice service." Law enforcement was exempted from the rule. Engel's bill passed in the House of Representatives. Nelson's bill was referred to the same Senate committee that approved S.704.[2][3] The Senate again passed neither version of the legislation.[4]

In the 111th Congress, Congressman Engel and Senator Nelson once again introduced similar versions of the Caller ID legislation, H.R. 1258. The bill was reintroduced in the Senate on January 7, 2009, as S.30, the Truth in Caller ID Act of 2009, and referred to the same committee[5] The Senate and the House both passed their respective versions of the legislation, but on December 15, 2010 the House passed S.30 and sent the legislation to the President for a signature. On December 22, 2010, President Obama signed the bill into law. [6]

Under the bill, which also targets VOIP services, it becomes illegal "to cause any caller identification service to knowingly transmit misleading or inaccurate caller identification information with the intent to defraud, cause harm, or wrongfully obtain anything of value...." Forfeiture penalties or criminal fines of up to $10,000 per violation (not to exceed $1,000,000) could be imposed. [7] The bill maintains an exemption for blocking one's own outgoing caller ID information, and law enforcement isn't affected. [8]


Caller ID spoofing has been available for years to people with a specialized digital connection to the telephone company, called an ISDN PRI circuit. Collection agencies, law-enforcement officials, and private investigators have used the practice, with varying degrees of legality.

The first mainstream Caller ID spoofing service,, was launched in September 2004. was the first service to allow spoofed calls to be placed from a web interface. It stopped offering service in 2005, as a handful of similar sites were launched.

In August 2006, Paris Hilton was accused of using caller ID spoofing to break into a voicemail system that used caller ID for authentication.[9] Caller ID spoofing also has been used in purchase scams on web sites such as Craigslist and eBay. The scamming caller claims to be calling from Canada into the U.S. with a legitimate interest in purchasing advertised items. Often the sellers are asked for personal information such as a copy of a registration title, etc., before the (scamming) purchaser invests the time and effort to come see the for-sale items. In the 2010 election, fake caller IDs of ambulance companies and hospitals were used in Missouri to get potential voters to answer the phone. [10] In 2009, a vindictive Brooklyn wife spoofed the doctor’s office of her husband’s lover in an attempt to trick the other woman into taking medication which would make her miscarry. [11]

Frequently, caller ID spoofing is used for prank calls. For example, someone might call a friend and arrange for "The White House" to appear on the recipient's caller display. In December 2007, a hacker used a Caller ID spoofing service and was arrested for sending a SWAT team to a house of an unsuspecting victim.[12] In February 2008, a Collegeville, Pennsylvania man was arrested for making threatening phone calls to women and having their home numbers appear "on their caller ID to make it look like the call was coming from inside the house."[13][14] Some companies even feature voice changing and call recording features. [15]

In March 2008, several residents in Wilmington, Delaware reported receiving telemarketing calls during the early morning hours, when the caller had apparently spoofed the Caller ID to evoke the 1982 Tommy Tutone song 867-5309/Jenny.[16]

Valid reasons to spoof caller ID

There are legitimate reasons for modifying the caller ID sent with a call.

  1. Calls from a large company, especially with multiple branches, where sending the main number makes sense. For example, a hospital might have the primary number 555-1000, with perhaps 250 lines inside the main building, and another 100 at the clinic five miles away. While some of the phones will have "555-10XX" numbers, many won't have any identifiable line. Having all calls "come from" 555-1000 lets the recipients know it's a hospital call.
  2. Commercial answering-service bureaus which forward calls back out to a subscriber's cell phone, when both parties would prefer the Caller ID to display the original caller's information.
  3. Most calling-card companies display the Caller ID of the calling-card user to the called party.
  4. Business owners have been known to use Caller ID spoofing to display their business number on the Caller ID display when calling from outside the office (for example, on a mobile phone).
  5. Skype users can assign a Caller ID number in order to prevent their Skype-Out calls being screened by the called party (the default Skype Caller ID in the USA is 0000123456).
  6. Google Voice displays its users' Google Voice number when they place calls through the service using their landline or cell phone.
  7. Gizmo5 sends the user's Gizmo5 SIP number as outbound Caller ID on all calls. Because Gizmo5 IDs are in the format 747NXXXXXX, it is possible to confuse calls made from Gizmo5 with calls made from area code 747.
  8. The New York Times sent the number 111-111-1111 for all calls made from its offices until 15 August 2011. The fake number was intended to prevent the extensions of its reporters appearing in call logs, and thus protect reporters from having to divulge calls made to anonymous sources. The Times abandoned this practice because of the proposed changes to the caller ID law, and because many companies were blocking calls from the well-known number.[17]


  1. ^
  2. ^ Senate Bill S.704. Retrieved from
  3. ^ House Bill HR251. Retrieved from
  4. ^
  5. ^
  6. ^
  7. ^ "Don't Believe Your Eyes: Spoofing"
  8. ^
  9. ^ Paris Hilton accused of voice-mail hacking | InfoWorld | News | 2006-08-25 | By Robert McMillan, IDG News Service
  10. ^ Kansas City Star, “Fake called IDs used in Missouri elections” David A. Lieb, Associated Press. Sun. Nov. 14, 2010.
  11. ^ "Virginia girl found eating herself in cage in mobile home; parents Brian and Shannon Gore charged". Daily News (New York). 
  12. ^ Hacking caller id systems on the rise -
  13. ^ KYW Newsradio 1060 Philadelphia - Man Pleads Guilty to Making Scary Phone Calls (link rot)
  14. ^ Actual Headline: "Man Pleads Guilty to Making Scary Phone Calls"
  15. ^ "Don't Believe Your Eyes: Spoofing"
  16. ^ Telemarketer's Call Invokes Old Hit Song, (Associated Press, March 11, 2008)
  17. ^ Peters, Jeremy W. (12 August 2011). "At The Times, Era of ‘111-111-1111’ Nears Its End". The New York Times (Media Decoder blog). Retrieved August 12, 2011. 

Further reading

Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Caller ID — (caller identification, CID), also called calling line identification (CLID) or calling number identification (CNID) or Calling Line Identification Presentation (CLIP), is a telephone service, available in analog and digital phone systems and… …   Wikipedia

  • Spoofing attack — In the context of network security, a spoofing attack is a situation in which one person or program successfully masquerades as another by falsifying data and thereby gaining an illegitimate advantage. Man in the middle attack and internet… …   Wikipedia

  • ISDN Spoofing — Die Artikel Call ID Spoofing und Vermittlungstechnische Leistungsmerkmale (öffentliche Netze)#.C3.9Cbermittlung kundenspezifischer Rufnummerninformationen .28CLIP no screening .29 überschneiden sich thematisch. Hilf mit, die Artikel besser… …   Deutsch Wikipedia

  • Call ID Spoofing — Der Begriff Call ID Spoofing bezeichnet die Methode, mit der Anrufe unter einer für den Angerufenen vorgetäuschten rufenden Nummer geführt werden kann. Dabei wird bei einer Rufnummernanzeige des angerufenen Telefons anstatt der Originalrufnummer… …   Deutsch Wikipedia

  • Spoof — Spoof, spooves, spoofer or spoofing can refer to: *Parody by imitation *Forgery of goods or documents *Spoofing attack, a computer security term *Referer spoofing, a type of spoofing attack *Protocol spoofing, a technique to increase performance… …   Wikipedia

  • Enterprise FMC — In the 2004 press release announcing its formation, the [ Fixed Mobile Convergence Alliance] said:Fixed Mobile Convergence is a transition point in the telecommunications industry that will finally remove the distinctions… …   Wikipedia

  • Fixed-mobile convergence — (FMC) is a change in telecommunications that removes differences between fixed and mobile networks. In the 2004 press release announcing its formation, the Fixed Mobile Convergence Alliance said:[1] Fixed Mobile Convergence is a transition point… …   Wikipedia

  • Phone fraud — Whether in the form of the consumer attempting to defraud the telephone company, the telephone company attempting to defraud the consumer, or a third party attempting to defraud either of them, fraud has been a part of the telephone system almost …   Wikipedia

  • Prank call — A prank call (also known as a prank phone call or crank call) is a form of practical joke committed over the telephone. Prank phone calls began to gain an America wide following over a period of many years, as they gradually became a staple of… …   Wikipedia

  • call laundering — pp. Hiding the identity of a caller or making a phone call untraceable. Example Citations: Telemarketers increasingly are disguising their real identities and phone numbers to provoke people to pick up the phone. Humane Soc. may not be the Humane …   New words

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”