A set-top box (STB) or set-top unit (STU) is an information appliance device that generally contains a TV-tuner input and displays output to a television set and an external source of signal, turning the source signal into content in a form that then be displayed on the television screen or other display device. They are used in cable television, satellite television, and over-the-air television systems, as well as other uses.
In telecommunication, a calling-party camp-on is a service feature that enables the telephone exchange to complete an access attempt in spite of temporary unavailability of system transmission or switching facilities required to establish the requested access.
A terminal emulator, terminal application, or term, is a program that emulates a video terminal within some other display architecture. Though typically synonymous with a shell or text terminal, the term terminal covers all remote terminals, including graphical interfaces. A terminal emulator inside a graphical user interface is often called a terminal window.
Direct memory access (DMA) is a feature of computer systems that allows certain hardware subsystems to access main system memory, independent of the central processing unit (CPU).
Phreaking is a slang term coined to describe the activity of a culture of people who study, experiment with, or explore telecommunication systems, such as equipment and systems connected to public telephone networks. The term phreak is a sensational spelling of the word freak with the ph- from phone, and may also refer to the use of various audio frequencies to manipulate a phone system. Phreak, phreaker, or phone phreak are names used for and by individuals who participate in phreaking.
Caller ID, also called calling line identification (CLID), Calling Line Identification (CLI), calling number delivery (CND), calling number identification (CNID), calling line identification presentation (CLIP), or call display, is a telephone service, available in analog and digital telephone systems, including VoIP, that transmits a caller's telephone number to the called party's telephone equipment when the call is being set up. The caller ID service may include the transmission of a name associated with the calling telephone number, in a service called CNAM. The service was first defined in 1993 in International Telecommunication Union - Telecommunication Standardization Sector (ITU-T) Recommendation Q.731.3.
In computer science, a semaphore is a variable or abstract data type used to control access to a common resource by multiple processes in a concurrent system such as a multitasking operating system. A semaphore is simply a variable. This variable is used to solve critical section problems and to achieve process synchronization in the multi processing environment. A trivial semaphore is a plain variable that is changed depending on programmer-defined conditions.
Automatic number identification (ANI) is a feature of a telecommunications network for automatically determining the origination telephone number on toll calls for billing purposes. Automatic number identification was originally created by AT&T Corporation for internal long distance charging purposes, eliminating the need for telephone operators to manually request the number of the calling party for a toll call.
A toll-free telephone number or freephone number is a telephone number that is billed for all arriving calls instead of incurring charges to the originating telephone subscriber. For the calling party, a call to a toll-free number from a landline is free of charge.
The public switched telephone network (PSTN) is the aggregate of the world's circuit-switched telephone networks that are operated by national, regional, or local telephony operators, providing infrastructure and services for public telecommunication. The PSTN consists of telephone lines, fiber optic cables, microwave transmission links, cellular networks, communications satellites, and undersea telephone cables, all interconnected by switching centers, thus allowing most telephones to communicate with each other. Originally a network of fixed-line analog telephone systems, the PSTN is now almost entirely digital in its core network and includes mobile and other networks, as well as fixed telephones.
Signals are a limited form of inter-process communication (IPC), typically used in Unix, Unix-like, and other POSIX-compliant operating systems. A signal is an asynchronous notification sent to a process or to a specific thread within the same process in order to notify it of an event that occurred. Signals originated in 1970s Bell Labs Unix and have been more recently specified in the POSIX standard.
An intercom, talkback or doorphone is a stand-alone voice communications system for use within a building or small collection of buildings, functioning independently of the public telephone network. Intercoms are generally mounted permanently in buildings and vehicles. Intercoms can incorporate connections to public address loudspeaker systems, walkie talkies, telephones, and to other intercom systems. Some intercom systems incorporate control of devices such as signal lights and door latches.
Nios II is a 32-bit embedded-processor architecture designed specifically for the Altera family of field-programmable gate array (FPGA) integrated circuits. Nios II incorporates many enhancements over the original Nios architecture, making it more suitable for a wider range of embedded computing applications, from digital signal processing (DSP) to system-control.
Remote File Sharing (RFS) is a discontinued distributed file system developed by AT&T in the 1980s. It was first delivered with UNIX System V Release 3 (SVR3). It was also included in AT&T's UNIX System V Release 4, but as that also included NFS which was more interoperable, RFS was little used. Some licensees of AT&T's UNIX System V Release 4 didn't include the RFS support in their SVR4 distributions, and Sun Microsystems removed it from Solaris 2.4.
In computer science, the event loop, message dispatcher, message loop, message pump, or run loop is a programming construct that waits for and dispatches events or messages in a program. It works by making a request to some internal or external "event provider", and then it calls the relevant event handler. The event-loop may be used in conjunction with a reactor, if the event provider follows the file interface, which can be selected or 'polled'. The event loop almost always operates asynchronously with the message originator.
WhatsApp Messenger is a freeware and cross-platform messaging and Voice over IP (VoIP) service owned by Facebook. The application allows the sending of text messages and voice calls, as well as video calls, images and other media, documents, and user location. The application runs from a mobile device but is also accessible from desktop computers; the service requires consumer users to provide a standard cellular mobile number. Originally, users could only communicate with others individually or in groups of individual users, but in September 2017, WhatsApp announced a forthcoming business platform that will enable companies to provide customer service to users at scale.
Communications-based train control (CBTC) is a railway signaling system that makes use of the telecommunications between the train and track equipment for the traffic management and infrastructure control. By means of the CBTC systems, the exact position of a train is known more accurately than with the traditional signaling systems. This results in a more efficient and safe way to manage the railway traffic. Metros are able to improve headways while maintaining or even improving safety.
Signal is an encrypted communications app for Android, iOS, Linux, Windows, and macOS. It uses the Internet to send one-to-one and group messages, which can include files, voice notes, images and videos, and make one-to-one voice and video calls.
