Introduction to vswitches

In communication, information exchange mainly refers to the switching or distribution process of information between different lines, terminals or networks. If there are n user groups in the communication network, the information of a user terminal must be switched to another specific user terminal through one or more nodes of the network. The common method is peer-to-peer. the user who receives the information must make a response or exchange further information with the other party, the information sent from the terminal must also be sent back to the sender's user through the node in the network to complete information exchange between the two parties. Therefore, the node that completes the information exchange function is called the exchange center or the exchange board, and the device that completes the information exchange and connection in the node is called the telephone exchange ).

Switch Development History
In 1876, Alexander Graham Bell, an American, imagined a method to change the sound vibration into the current, and invented the phone.
In 1879, The United States designed and made the first magnet telephone switch, also known as a self-contained Battery switch.
In 1891, a co-electric telephone switch emerged. The difference between a co-electric switch and a tile-stone switch mainly canceled the Dry Battery Used by the user. All calls were centrally provided by the battery in the Bureau, therefore, it is also known as the shared battery type, referred to as the co-electric type.
A self-contained Battery switch and a common electrical switch require manual help.
In 1891, American Shi Duan Qiao invented the first automatic telephone switch, and later called Shi Duan Qiao automatic switch. After the first launch in the United States, the sendon automatic switch was introduced to the UK, Germany and other countries, and the SIEMENS Automatic telephone switch was improved.
The above two types of automatic telephone switches are directly controlled by the dial pulse to connect to the switch, step by step, and one step to the ground and rotate for wiring. Therefore, they are called step by step. In terms of control mode, hierarchical control or direct control is also called.
In 1914, the United States made a rotating automatic switch, referred to as a rotating switch. The main difference between a rotating telephone switch and a stepping switch is that the rotation system uses a record generator. Instead of directly controlling the action of a dial, the dial pulse is recorded by the record generator, then forward and select and connect. Therefore, the control mode is called the indirect control mode. In either step or rotation mode, the secondary node needs to be scaled up and rotated. It is dry, easy to wear, and heavy maintenance workload.
An automatic telephone switch, short for the vertical and horizontal system, adopts reasonable electromechanical connectors and highly efficient public control devices.
In early 1950s, the development and development of the vertical and horizontal switch system had reached a relatively mature stage. The large number of vertical and horizontal switches and relays are still electromagnetic components. Therefore, the aforementioned stepping and rotating switches can be collectively referred to as electromechanical switches. However, in electromechanical mode, vertical and horizontal systems are the most advanced and are still used for production and installation in some countries.
Electromagnetic relays are the basic components of the control circuit in electromechanical switches. With the development of transistors and integrated circuits, the electronic exchange system is an inevitable trend. The main device of the switching system is composed of a telephone device and a control device. The electronic communication of telephone devices is not smooth, and the electronic control equipment is easy to implement. With the development of electronic devices and integrated technology, the rapid development of electronic computers has basically changed the electronic switches of traffic control, it entered the era of programmable switches.
A Programmable switch (SPC) is a storage device. Program The short name of the control switch (stored program controled switching. It uses electronic computer technology to control switch connection operations with pre-compiled programs. A Programmable switch is a telephone switch controlled by an electronic computer.