Caller ID (caller identification, CID), also called calling line identification (CLID), calling number delivery (CND), calling number identification (CNID) or calling line identification presentation (CLIP), is a telephone service, available in analog and digital phone systems and most voice over Internet Protocol (VoIP) applications, that transmits a caller's number to the called party's telephone equipment during the ringing signal, or when the call is being set up but before the call is answered. Where available, caller ID can also provide a name associated with the calling telephone number. The information made available to the called party may be displayed on a telephone's display, on a separately attached device, or personal computer.
Caller ID information typically consists of the caller's telephone number and the caller's name. A modem can pass CLID information to a computer for purposes of call logging or blocking, but this can be problematic as modems in different countries have different systems, causing hardware or software incompatibilities. However, many modems are designed and programmed to handle multiple signalling methods, and can be configured to use the local standard.
The North American Numbering Plan (NANP) is an integrated telephone numbering plan that encompasses 25 countries and territories primarily in North America, the Caribbean, and U.S. territories.
The NANP is a standardized system of numbering plan areas (NPA) using telephone numbers consisting of three-digit area code, a three-digit central office code, and a four-digit station number. Through this plan, telephone calls can be directed to particular regions of the larger NANP public switched telephone network (PSTN), where they are further routed by the local networks. The NANP is administered by the North American Numbering Plan Administration (NANPA), a service operated by Neustar corporation. The international calling code for the NANP is 1. Not all North American countries participate in the NANP.
A telephone number is a unique sequence of digits assigned to each telephone subscriber station, telephone line, or since the advent of digital telephony to an electronic telephony device, such as a mobile telephone. The telephone number serves as the address to switch telephone calls using a system of destination routing. It is entered or dialed by the calling party on the originating telephone set which transmits it in the process of signaling to a telephone exchange which completes the call either to another locally connected subscriber or via the public switched telephone network (PSTN) to the called party.
The concept of using telephone numbers instead of subscriber names when connecting calls was developed and first used between 1879 and 1880 in Lowell, MA, for the purpose of ease of training new telephone operators.
A rotary dial is a component of a telephone or a telephone switchboard that implements a signaling technology in telecommunications known as pulse dialing. It is used when initiating a telephone call to transmit the destination telephone number to a telephone exchange.
On the rotary dial, the digits are arranged in a circular layout so that a finger wheel may be rotated with one finger from the position of each digit to a fixed stop position (finger stop). When released at the finger stop, the wheel returns to its home position by spring action at a speed regulated by a governor device. During this return rotation, the dial interrupts the direct electrical current of the telephone line (local loop) a specific number of times for each digit and thereby generates electrical pulses that the telephone exchange decodes into each dialed digit. Each of the ten digits are encoded in sequences of up to ten pulses. For this reason, the method is sometimes called decadic dialling.
A vertical service code (VSC) is a special code dialed prior to (or instead of) a telephone number that engages some type of special telephone service or feature. Typically preceded with an asterisk, or * (star), key on the touch tone keypad and colloquially referred to as star codes, most are two digits in length; as more services are developed, those that use 2 or 3 as the first digit are sometimes three digits in length.
In North American telephony, VSCs were developed by AT&T Corp. as Custom Local Area Signaling Services or CLASS codes (sometimes LASS) in the 1960s and 70s. Their use became ubiquitous throughout the 1990s and eventually became a recognized standard. As CLASS was an AT&T trademark, the term "vertical service code" was adopted by the North American Numbering Plan Administration. The use of the word "vertical" is a somewhat dated reference to older switching methods and the fact that these services can only be accessed by a local telephone subscriber, going up (or vertically) inside the local central office instead of out (or horizontally) to another telephone company.
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.
Call capture is a telephone-based technology that captures personal data from persons who call a properly provisioned number. After the call is placed, the system notifies a client of the name, phone number and address of the person calling. The system was designed as a device for real estate agents and allows one to legally bypass do not call laws.
Real estate agents for example might display their 800 call capture phone number on a signrider (small, sometimes 12 × 30 sign that sits on top of the For Sale sign in a house owner's yard), with a call to action like "Free Recorded Information—Call 24 hours". When someone drives by, notices the sign, writes the phone number down and calls on his cell phone or land line, they are greeted by the real estate agent's personal greeting, directed to dial in the 4-digit extension for the home they are interested in. Then, they listen to a 45–60 second "audio tour" of the home.
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite (TCP/IP) to serve several billion users worldwide. It is a network of networks that consists of millions of private, public, academic, business, and government networks, of local to global scope, that are linked by a broad array of electronic, wireless and optical networking technologies. The Internet carries an extensive range of information resources and services, such as the inter-linked hypertext documents of the World Wide Web (WWW), the infrastructure to support email, and peer-to-peer networks.
Most traditional communications media including telephone, music, film, and television are being reshaped or redefined by the Internet, giving birth to new services such as voice over Internet Protocol (VoIP) and Internet Protocol television (IPTV). Newspaper, book and other print publishing are adapting to website technology, or are reshaped into blogging and web feeds. The Internet has enabled and accelerated new forms of human interactions through instant messaging, Internet forums, and social networking. Online shopping has boomed both for major retail outlets and small artisans and traders. Business-to-business and financial services on the Internet affect supply chains across entire industries.