City telephony cannot do without such an important element as a communication center. It represents a number of technical means that are used by the telecom operator to provide high-quality telecommunication services. It is a question of various services (automatic telephone exchange, WEB, etc.), and also routers necessary for ensuring connection with provider.
From a physical point of view, the node is located in a large rack; routers and servers are also installed in it. For its placement, they usually choose a separate room, they maintain the optimum temperature for work, and also specialists with insufficient qualifications are not allowed there. As a rule, such a design should be placed in a building located in the central part of the city. In the same house, most often there are those institutions that need stable communications, but do not have their own telephone exchange, we are talking about public points for access to the Internet, post offices, as well as telegraphs.
Background: 19th Century
The appearance of the first communication nodes should be attributed to the end of the XIX century, it was then that the telephone was invented by the American scientist Alexander Bell . Already in 1877, the active production of telephones with two handsets began, which were connected to each other using wires and were in the same room or house. At first, this system was very popular, but soon there was an urgent need to connect several talk lovers at once.
It was then that switchboards were created that were controlled manually. The owner of the device picked up the phone, then twisted the handle, after which his call immediately fell on the operator on duty, then they worked mainly girls. The telephone operator needed to voice the name of the person with whom the subscriber wanted to talk, and then she connected the two parts of the cable together in order for the conversation to take place.
Background: XX century
By the beginning of the 20th century, regional communication centers appeared, in which 40-50 telephone operators worked simultaneously, they had to connect all the contacting subscribers around the clock. The work was quite laborious and requiring a large amount of resources, so soon the question arose again about how to translate it all into an automatic way.
Only in the early 1920s, inventors managed to achieve the possibility of a direct connection between two subscribers. It was then that disks with numbers that were used to dial the numbers began to be embedded in telephone sets. The equipment providing communication between subscribers has also undergone major modernization, if at the beginning of the 20th century it could occupy an entire floor, now a five-meter room is enough to accommodate it.
Nodes today
The telephone communication center today is a number of automatic stations that are able to provide a connection between two subscribers without the participation of additional human resources. Moreover, it should be universal and be able to maintain communication not only with subscribers who are connected only to it, but also with others that are served by other telephone exchanges.
A well-designed PBX structure is capable of supporting the connection process between devices for a long time, as well as providing a number of additional features. This effect is achieved through the use of telephone alarms, as well as continuous improvement of the system.
How do site components work?
Large cities are mainly served by regional communication centers, which should have a large number of functions. First of all, it is about the equipment on the node recognizing a call signal from a system user who needs outgoing communication. The subscriber hears a continuous beep, which is a signal that the system is ready to receive information for further actions. As soon as the user dials the number he needs, the system must remember him.
Then the search for the dialed combination occurs, while all the elements of the number that are involved in it are temporarily marked and become busy. This is necessary so that no one else can talk to this number at the same time. In the event that the elements (or paths) of the number are busy, the caller will hear the corresponding signal in the form of frequent beeps. In this case, you will need to try again later.
How is receiving communication arranged?
The elements of the communication node are aimed at connecting the selected communication channel as soon as possible. That is why with their help, the called subscriber is informed about the call. At the same moment, the client of the system who decided to use the outgoing call receives a tone informing him of the call attempt. This beep is duplicated with an interval of 4 seconds if the called user does not pick up the phone.
As soon as the call on the other hand is accepted, the system automatically connects both users to the path and provides the ability to talk. Here it is necessary to take into account a number of restrictions, in particular the fact that the nodes serve not only landline telephony, but also mobile phones. The latter may have a limit on the duration of the conversation of 30 minutes, detailed information about this must be clarified with the operator.
As soon as the dialogue has been completed, the communication node receives a corresponding signal about its termination. Further, the process occurs in the reverse order - all the elements used in the construction of the communication path are disconnected, the marking of the number components is disabled. That is how a telephone connection is made between two subscribers, with the advent of conference calls their number can increase to five or more.
Varieties of knots: USSR
The very first communication centers consisted of automatic telephone exchanges, which were a large machine drive of a large number of shafts. Their design was such that a particularly annoying subscriber could connect to the number in a very congested direction, while he did not have to call back, but just had to hold the phone at his ear for a long time and wait.
After World War II, they began to be replaced by decade-step stations with complex electromechanical devices. When using them, a significant drawback was revealed - a large number of interference, so they were soon replaced by coordinate ones. The latter began to use markers and registers, greatly simplifying the process of storing numbers and connections between subscribers.
Varieties of nodes: Russia
After the collapse of the USSR, quasi-electronic stations began to appear, which had improved communication quality, some of which still work. Very popular today are electronic telephone exchanges, which are divided into analog and digital. The former are used on small nodes with a small number of subscribers and have very low immunity to interference.
Digital, which are installed on most urban communication centers, completely translate the signal into the desired format and transmit it to each other almost in its original form. Due to this, it is possible to reduce the amount of interference, as well as to avoid signal attenuation during the dialogue. Not so long ago, IP-telephony began to be widely used, where it is customary to use packet switching, due to this, telephone exchanges called IP-ATS appeared.
And what about the post office?
Mail communication nodes are organized according to a similar principle, messages are received and transmitted using modems that are on the same network as the computers of the organization’s employees, this system is called “Telex”. To transfer data, it is customary to use it, as well as e-mail. The wire telegraph network practically no longer exists in Russia; its active dismantling began in the early 2000s and continues to this day.
In European countries, the telegraph has long been called obsolete and has ceased to engage in its maintenance. In Holland, he stopped working in 2006, in India - in 2013, and in 2017, Belgium refused him. Some US postal operators also refused to use this type of communication, however, in Japan, Germany, Sweden, Canada and other countries, the telegraph regularly carries the function assigned to it.
How to organize this node: room
If you own your own telephone exchange, the organization of a communication center is the very first thing you need to do. You need to start by choosing the right room for its placement, it does not have to be large, the main thing is that the floor must withstand the load that you planned. Place cabinets, racks and racks so that they do not interfere with each other and their parts do not touch. Be sure to install the air conditioning system and its reserve in order to avoid overheating of the PBX and their failure.
Above the premises should not be located communications along which water passes, and the floors in it must necessarily be made fireproof. If there are windows in the future site, they need to be tinted or covered with plywood, since it is undesirable to get sunlight on the equipment. The room should have good lighting, all metal structures must be earthed and additionally fenced off with materials that do not conduct current. It is also recommended to place dielectric rubber carpets, carbon dioxide type fire extinguishers and a first aid kit in the room.
How to organize a communication center: racks and cabinets
What is required for further work? The scheme of communication nodes that will be located in the room should be as convenient and understandable not only to you as a person who is constantly working with electrical equipment, but also to a completely unauthorized visitor. That is why it is best to take care of placing all stations and servers in racks and cabinets in advance. Avoid using cabinets that are too tall because they may not withstand the weight of the equipment and fall over. If a small space does not allow you to put several racks and you have to install all the equipment in one, then it is better to additionally fix the shelves.
Inside each cabinet or rack, vertical organizers should be installed, with their help it will be much easier to bring optics and power to the equipment. You can assemble the equipment yourself, if necessary, you can purchase it in a store, order delivery and assembly, so as not to waste your time. Remember that racks and cabinets with telephone exchanges and servers should be located at a remote distance from windows and air conditioning systems.
It doesn’t matter what you are building: a regional communications center or a city one, in any case, it is necessary to immediately create reserve capacities. In the event that one of the nodes becomes unusable, you can immediately transfer the load to the backup one. Particular attention should be paid to the fact that only those who have the appropriate access can have access to the premises you have built, this is a mandatory requirement of the Ministry of Information Communications.
Conclusion
If you are a small operator providing communication services to a limited number of subscribers, you can register your equipment using a simplified scheme. Now it is not necessary to create documentation for absolutely all the systems of your station, which is very convenient - one photo of the communication center is enough to build it. However, all requirements must be met, because technical supervision can come to you with an audit at any time.
Follow simple safety rules when creating a site, this is guaranteed to protect you from troubles and accidents. Your room must be tight; you will need to purchase a vacuum cleaner to clean it, wet cleaning will not be possible here. Be sure to sign all the elements of the unit, hang the signs on the cabinets and racks, place the evacuation scheme so that all employees know what to do in case of danger.