Caller ID Spoofing

Caller ID Spoofing 

Caller ID spoofing is the practice of causing the telephone network to indicate to the receiver of a call that the originator of the call is a station other than the true originating station. For example, a Caller ID display might display a phone number different from that of the telephone from which the call was placed. The term is commonly used to describe situations in which the motivation is considered malicious by the speaker or writer.

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.

Voice over IP

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 orFreeSWITCH, and almost any VoIP company), one can spoof calls with minimal costs and effort.

Some VoIP providers allow the user to configure their displayed number as part of the configuration page on the provider's web interface. No additional software is required. If the caller name is sent with the call (instead of being generated from the number by a database lookup at destination) it may be configured as part of the settings on a client-ownedanalog telephone adapter or SIP phone. The level of flexibility is provider-dependent. A provider which allows users to bring their own device and unbundles service so that direct inward dial numbers may be purchased separately from outbound calling minutes will be more flexible. A carrier which doesn't follow established hardware standards (such asSkype) or locks subscribers out of configuration settings on hardware which the subscriber owns outright (such as Vonage) is more restrictive. Providers which market "wholesale VoIP" are typically intended to allow any displayed number to be sent, as resellers will want their end user's numbers to appear.

In rare cases, a destination number served by voice-over-IP is reachable directly at a known SIP address (which may be published through ENUM telephone number mapping, a.tel DNS record or located using an intermediary such as SIP Broker). Some Google Voice users are directly reachable by SIP, as are all iNum Initiative numbers in country codes +883 5100 and +888. As a Federated VoIP scheme provides a direct Internet connection which does not pass through a signaling gateway to the public switched telephone network, it shares the advantages (nearly free unlimited access worldwide) and disadvantages (ernet applications.)

Service providers

Some spoofing services work similarly to a prepaid calling card. Customers pay in advance for a personal identification number (PIN). Customers dial the number given to them by the company, their PIN, the destination number and the number they wish to appear as the Caller ID. The call is bridged or transferred and arrives with the spoofed number chosen by the caller—thus tricking the called party.

Many providers also provide a Web-based interface or a mobile application where a user creates an account, logs in and supplies a source number, destination number and the bogus caller ID information to be displayed. The server then places a call to each of the two endpoint numbers and bridges the calls together.

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

Orange box

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 an incoming caller ID prior to answering and relies to a certain extent on the guile of the caller, it is considered as much a social engineeringtechnique 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.