Caller ID spoofing

Caller ID spoofing is the practice of causing the telephone network to display a number on the recipient's caller ID display which is not that of the actual originating station; the term is commonly used to describe situations in which the motivation is considered nefarious by the speaker. 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 people are prone to assume a call is coming from the number (and hence, the associated person, or persons), this can call the service's value into question.

Providers

To use a typical service, a customer pays in advance for a PIN allowing them to make a call for a certain amount of minutes. To begin, the customer dials from any phone the toll free number given to them by the company and enters their PIN. They are then asked to enter the number they wish to call and the number they wish to appear on the caller ID. Once the "customer" selects the options, the call is then bridged and the person on the other end assumes someone else is calling them.

Many Caller ID spoofing service providers also allow customers to initiate spoofed calls from a web based interface in addition to calling a toll free number and entering the ten digit number you want to display followed by the ten digit number you want to call. Some providers allow you to enter the name you would like to display along with the spoofed Caller ID number but in most parts of the country, 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.

Using a web based spoofing form 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

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

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

Technology & 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 Voice over IP 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 SS7 network, and social engineering telephone company operators into placing calls for you from the desired phone number. Another method that is not used as often is VXML which was gaining popularity before VoIP took over.

History

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, Star38.com, was launched in September 2004. Star38.com 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 using the SpoofCard service [1].

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.

There are legitimate reasons for modifying the caller ID sent with a call, such as commercial answering service bureaus which forward calls back out to a subscriber's cell phone, when both parties would prefer the CNID to display the original caller's information. Also, business owners have been known the use Caller ID spoofing to display their business number on the Caller ID display when calling from outside the office, on a mobile phone for example.

External links

• Verizon Spoofing Article
• BBC News
• Washington Post
• Bruce Schneier
• Wired News report of FCC investigation
• SecurityFocus (also mentions override of Caller ID blocking)
• Additional information on Caller ID spoofing