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.
Pulse dialing is a signaling technology in telecommunications in which a direct current local loop circuit is interrupted according to a defined coding system for each signal transmitted, usually a digit. This lends the method the often used name loop disconnect dialing. In the most common variant of pulse dialing, decadic dialing, each of the ten Arabic numerals are encoded in a sequence of up to ten pulses. The most common version decodes the digits 1 through 9, as one to nine pulses, respectively, and the digit 0 as ten pulses. Historically, the most common device to produce such pulse trains is the rotary dial of the telephone, lending the technology another name, rotary dialing.
Direct distance dialing (DDD) is a telecommunication service feature in which a caller may, without operator assistance, call any other user outside the local calling area. Direct dialing by subscribers typically requires extra digits to be dialed as prefixes than for dialing within the local area or within an area code. DDD also extends beyond the boundaries of national public telephone network, in which case it is called international direct dialing or international direct distance dialing (IDDD).
In telecommunications, an electronic switching system (ESS) is a telephone switch that uses solid-state electronics, such as digital electronics) and computerized common control, to interconnect telephone circuits for the purpose of establishing telephone calls.
In electronics, a crossbar switch is a collection of switches arranged in a matrix configuration. A crossbar switch has multiple input and output lines that form a crossed pattern of interconnecting lines between which a connection may be established by closing a switch located at each intersection, the elements of the matrix. Originally, a crossbar switch consisted literally of crossing metal bars that provided the input and output paths. Later implementations achieved the same switching topology in solid state semiconductor chips or System on Chips (SoC). The cross-point switch is one of the principal switch architectures, together with a rotary switch, memory switch, and a crossover switch.
The Strowger switch is the first commercially successful electromechanical stepping switch telephone exchange system. It was developed by the Strowger Automatic Telephone Exchange Company founded in 1891 by Almon Brown Strowger. Because of its operational characteristics it is also known as a step-by-step (SXS) switch.
Automatic Electric Company (AE) was the largest of the manufacturing units of the Automatic Electric Group. It was a telephone equipment supplier for independent telephone companies in North America, and also had a worldwide presence. With its line of automatic telephone exchanges, it was also a long-term supplier of switching equipment to the Bell System, starting in 1919.
The director telephone system was a development of the Strowger or step-by-step (SXS) switching system used in London and five other large cities in the UK from the 1920s to the 1970s.
A sender was a special type of circuit in 20th-century electromechanical telephone exchanges which registered the telephone numbers dialed by the subscriber, and then transmitted that information to another exchange. In some American exchange designs, for example, the No. 1 Crossbar switch there were both originating senders and terminating senders. The corresponding device in the British director telephone system was called a "director" and, in other contexts, "register".
A business telephone system is a multiline telephone system typically used in business environments, encompassing systems ranging in technology from the key telephone system (KTS) to the private branch exchange (PBX).
A marker is a type of special purpose control system that was used in electromechanical telephone central office switches. Switches employing markers belong to a class of switches known as "common control", as the purpose of a marker is to control the closure of contacts in the switching fabric that connect a circuit between the calling party and the called party. This is in contrast to "direct control" switches, where the switching elements were controlled directly by the customer's dial, such as the Step by Step switch. The term marker came from its use to mark a path of links through the switching fabric. A marker's comprehensive view of the switching fabric allowed it to find and assemble a path from one terminal to another, if the links were available, unlike the earlier graded progressive systems in which a path might not be found.
Stored program control (SPC) is a telecommunications technology used for telephone exchanges controlled by a computer program stored in the memory of the switching system. SPC was the enabling technology of electronic switching systems (ESS) developed in the Bell System in the 1950s, and may be considered the third generation of switching technology. Stored program control was invented by Bell Labs scientist Erna Schneider Hoover in 1954 who reasoned that computer software could control the connection of telephone calls.
The Number Five Crossbar Switching System is a telephone switch for telephone exchanges designed by Bell Labs and manufactured by Western Electric starting in 1947. It was used in the Bell System principally as a Class 5 telephone switch in the public switched telephone network (PSTN) until the early 1990s, when it was replaced with electronic switching systems. Variants were used as combined Class 4 and Class 5 systems in rural areas, and as a TWX switch.
The Number One Crossbar Switching System, was the primary technology for urban telephone exchanges in the Bell System in the mid-20th century. Its switch fabric used the electromechanical crossbar switch to implement the topology of the panel switching system of the 1920s. The first 1XB system was installed in the PResident-2 central office at Troy Avenue in Brooklyn, New York which became operational in February 1938.
TXE, was a family of telephone exchanges developed by the British General Post Office (GPO), designed to replace the ageing Strowger systems.
TXK was a range of Crossbar exchanges used by the British Post Office telephone network, subsequently BT, between 1964 and 1994. TXC was used as the designation at first, but this was later changed as TXC sounded too much like TXE the code used for later electronic exchanges. Prior to this the GPO had standardised on Strowger for automatic switching and had resisted the adoption of Crossbar, preferring to wait for its electronic switching research to bear fruit. The development of electronic systems however took longer than anticipated and the British equipment manufacturers, particularly Automatic Telephone & Electric (ATE), which later became part of the Plessey group feared that continuing to focus the bulk of their production on Strowger equipment would harm their export sales as Crossbar had already become popular throughout the world.
The Highgate Wood telephone exchange was the first all-electronic telephone exchange in Britain. It was built in the London suburb of Highgate by members from Joint Electronic Research Council (JERC).
A telephone exchange or telephone switch is a telecommunications system used in the public switched telephone network or in large enterprises. It interconnects telephone subscriber lines or virtual circuits of digital systems to establish telephone calls between subscribers.
The Panel Machine Switching System is an early type of automatic telephone exchange for urban service, introduced in the Bell System in the 1920s. It was developed by Western Electric Laboratories, the forerunner of Bell Labs, in the U.S., in parallel with the Rotary system at International Western Electric in Belgium before World War I. Both systems had many features in common.
