Caller identification services
Caller ID services identify the number, and sometimes the name, of an incoming call. It allows people to recognize who is calling prior to deciding whether to answer the call at the current moment. There are various reasons why one might not prefer to answer a call immediately depending on who is calling. One reason is for billing purposes, where a call can have a cost, and the call appears to be useless for the receiver, in which case they can save money by avoiding the useless call. Another reason is for time management, where one may recognize a caller and wish to speak with them, but do not currently have enough time. By waiting for when they have time to return the call, they may enjoy a longer conversation without needing to interrupt the call to postpone further exchange at a later date. In some cases, knowledge of the potential identity and purpose of an incoming call can promote safety. There has been an increase in telephone-related scams in recent years, where people target vulnerable people, using deception to cheat them of their money unfairly. These reasons and more make caller identification services an important feature.
There was a time when caller ID services common today did not exist. It wasn't until the 1980s that it became possible for people at home to see the phone number that was calling. At the time, there was a debate about the privacy implications.
One calling from home no longer has any way to preserve his anonymity, ... On the other hand, the services can safeguard one from heavy breathers, obscene callers and total strangers making cold-calls at the dinner hour...
— November 28, 1989, article in the Wall Street Journal
And then there are a variety of new devices which in a sense are truly revolutionary, for they finally return control of the phone to its owner from its long domination by every salesman, solicitor or crackpot who decides to call at any hour of the day or night. Thus, we now have phones which display the caller's number before the conversation has begun, allowing a decision to be made on the possible interruption in advance of any lifting of the receiver; phones that provide a distinctive ring when a call is made from a number that the owner of the instrument considers important or worthy of priority consideration; and instruments that completely and automatically block calls from persons with whom the phone's owner does not wish to speak. Ever since the telephone was invented, we have been in dread of not picking up a ringing telephone no matter whether we were engaged in eating dinner, in taking a bath, attending an important conference or an evening with friends or in some other activity that required calm or concentration without interruption. And so, whenever the phone rang, we generally interrupted, no matter what we were doing. The new features are ending this burden, this anomaly.
— Harold Greene during his acceptance speech for the Roscoe Barrow award at Hastings College of Law in 1987
Signaling System Seven (SS7) is a signaling technique used by carriers to route and manage telephone calls. It uses out-of-band signaling, where information is transmitted on a separate channel, not in-band where it was shared with the voice channel. SS7 was adopted by Local Exchange Carriers (LECs) in the early 1980s, and it is what makes caller ID possible.
In the 1990s, the Commission set rules that common carriers using SS7 call set-up capabilities must usually transport the calling party number (CPN) on interstate calls to interconnecting carriers. If a caller does not want to reveal their identity, they could dial *67, or 1167 for rotary phones without an asterisk key, before dialing the phone number they are calling. The carriers are then required to honor the request and hide the caller's identity.
Caller ID can be modified to hide or falsify the caller's identity. This can be utilized as part of deceptive techniques for tricking unsuspecting people. For example, someone can call using the number of a hospital, and pretend there is an emergency with a family member. They can pretend to call from the IRS, saying you are being audited. They can pretend to be calling from your bank, and ask for account details. They can even call law enforcement, using falsified caller identification and trick them into responding to an emergency that does not exist. The ability to modify the caller ID sent with a call has beneficial uses, such as using a business name when calling a client from your home office. It is not that caller ID itself is inherently harmful, but the malicious lies that are used as part of a separate harmful act. How can we keep the useful benefits of caller ID, and its modification, in a world where some are willing to utilize it for nefarious purposes that are amplified using computer and internet telecommunication technologies?
Setting a customized caller ID number and name became easier for most people with internet telephony services. Rather than SS7, Voice over Internet Protocol (VoIP) calls use the session initiation protocol (SIP). This puts the signalling in software, where details such as the caller ID can be modified in mass automations. For example, you can write code that automatically sets the outgoing caller ID number to a random number with the same local area code as the receiver. This can make the call appear more legitimate, because the person screening the call recognizes the area, whereas if it were any random number without personal relvance, they might be more likely to ignore the call as an unknown out of area mistake or telemarketing call. It is actually legal for telemarketers to modify the identity of the call, for legitimate purposes, such as using the name of the business they are calling on behalf of to promote, as long as they honor the do not call registry (DNCR).
The Truth in Caller ID Act of 2009 makes it unlawful for Americans to transmit fake caller ID for the purpose of defrauding, causing harm, or wrongly obtaining anything of value.
Automatic Number Identification (ANI) is the delivery of the calling party's billing number by a local exchange carrier to any interconnecting carrier for billing or routing purposes, and to the subsequent delivery of such number to end users.