Kaluga Telegraph Equipment Plant (part of the Ruselectronics holding) today is one of the modern developing enterprises with high technical and technological capabilities, capable of producing both single products of any complexity and mass production of up to 1.5 million products per year.

The plant's modern products - new generation communications equipment, mobile hardware communications and command and staff vehicles for defense departments and the Ministry of Emergency Situations, telemetry equipment, automotive electronics, telecommunication cabinets and racks, are distinguished by high quality and reliability.

The use of advanced technologies and the most modern imported equipment can significantly increase labor productivity, quality, reliability, raise the technical level, minimize production preparation time and ultimately increase the competitiveness of manufactured products.

Particular attention at the enterprise is paid to the introduction of special communications equipment of the new generation: P-166M technical warning systems, documentary communication and KShM hardware, P-112 color fax machines.

1. Hardware special documentary communication K-8M. Designed for organizing communications at field mobile communication centers of control points. The transport base of the equipment room is made on the basis of a K5350 van body on the chassis of a KAMAZ-5350 vehicle, which allows it to be used in field conditions, without being tied to the road network. The equipment room consists of two compartments: a compartment for the chief and equipment mechanic and a compartment for documentary communication operators - 4 workstations.

The company is installing an automated control system for the parachute battalion of the airborne division based on a unified command vehicle (BMD-2K). The system is designed to control battalion-level control units of an airborne division in various operational-tactical conditions and provides solutions to the problems of automating basic control processes, information and calculation tasks and information exchange.

2. Unit of the paratroopers collection device (BUSD).

3.

BUSD provides:
- transmission of commands to the radio station R-168-K-0.5MKM for the transition to the ZCH channels and temporary channels;
- exchange with the radio station R-168-K-0.5MKM of transmitted and received formalized messages;
- power supply to the radio station;
- exchange of formalized messages with the automated mobile unit (AMU) workstation;
- determination of the geographic coordinates of the AUV based on data from space navigation satellites and their transfer to subscribers of the paratrooper’s control system and to the AUV automated workstation;
- input and storage of setting parameters from the workstation.

4. The display and control unit (DCU) is part of the paratroopers’ collection device and is designed to work as part of a paratrooper’s wearable control system; it allows you to navigate the terrain without a map, because As the user moves towards the target, the coordinates of which are entered into the memory of the BOU, the distance to the target and the direction towards it are adjusted.

5. The company also produces fax machines for the needs of the RF Armed Forces. The P-112 fax machine combines the functions of a system printer, scanner and fax and is designed for transmitting, receiving and documenting color graphic and text information in the communication and data transmission systems of the Russian Armed Forces, as well as over the public switched telephone network. Designed for installation on stationary and moving objects.

6. OJSC "KZTA" has a powerful production base necessary for the production of electronic and electromechanical components and products.

7. Mechanical procurement production (high precision machining on automatic lathes, machining centers and CNC machines).

8. Laser cutting of metals and molding of the necessary parts on high-performance CNC pressing equipment, which allows you to minimize the time required for production preparation.

9.

10. Tool production has a wide range of high-precision equipment from leading domestic and foreign companies (MAZAK, Sodik), capable of fully meeting the organization’s needs for stamps, molds, casting forms, cutting and measuring tools in the shortest possible time.

11.

12. Assembly and installation production (including installation of surface-mounted radio elements) using a screen printing machine, an automatic PMI installation machine, a convection reflow oven and an automatic optical inspection system, a sealing section for printed circuit units using an automated line for the selective application of moisture-proof coatings with visual control of the quality of application.

13.

14.

The company pays special attention to supporting young specialists; a career planning system is in place for promising employees; many plant employees have been awarded departmental and state awards.

Today the plant is developing dynamically, new types of products are being developed not only for the needs of the Russian Ministry of Defense, the Ministry of Emergency Situations of the Russian Federation, but also for civilian use. The technical re-equipment of the enterprise is ongoing. It is safe to say that the Kaluga Telegraph Equipment Plant is a leading enterprise not only in the Kaluga region, but throughout Russia.

So, let’s pull on our robe, put on shoe covers and a hat, and set off on a journey to the underbelly of the Chinese economic miracle.

First work shift – 8 a.m.

All workers are divided into teams of 10-20 people, they have their own commander, who is a small god responsible for his people. The structure completely copies the army - there are no strong and weak here. Achievements are judged solely on how the entire team did their job. The work plan is set to a certain number of actions for each person - that is, formally you can do your thousand details and be free. In practice, the telephone assembly line is designed in such a way that production depends not only on your work, but also on what your comrades do - they hand over parts of the phone to you after their manipulations. This deceptive maneuver serves to increase labor productivity; if the team can mobilize all the workers, then their productivity will increase - but no one will be able to leave the workplace separately.

This is another part of the story that is often forgotten or overlooked. In Asia, historically, there are prerequisites for each nationality to create classes within itself - in India, these are the kshatriyas remembered from the school history course, as well as untouchables and others, in Japan - the modern caste system of belonging to one or another corporation or company. In China, factories have adopted approximately the same approach, but here the unit of the universe is the work team. An individual worker is a cog in a large machine who is not too interested in this machine and should not influence it; his task is only to be part of the whole. An absolutely army approach, in which a particular worker cannot express himself in any way; this is the task of the team - that is, the brigade. It is safe to say that on the social ladder, factory workers are somewhere at the very bottom. Sometimes the smartest ones, those who can organize the work of other workers, become foremen, sort of sergeants of the working world. What is valued here is not the speed of a particular person’s work, but how quickly the team manages its work. Individuality fades into the background.

A typical work day starts at 8 am. At this time, workers come to the workshops, which are located on several floors, and are built together with the foreman. Each team appears at a strictly allotted time - the gap between their exit is about 5 minutes, this is done so as not to create a crowd. Therefore, the time of 8 o’clock can be treated as a certain conditional milestone - the factory works around the clock, but on the night shift, if there is no force majeure, the number of workers is smaller.

Sleep is the most valuable thing a Chinese worker has, and he values ​​it very much - those who do not get enough sleep threaten the well-being of their comrades. The output of the entire team may suffer, which means that the working day will turn from a 10-hour day to an 11-hour day, or even longer. By law, the maximum working day is 10.5 hours. The best teams manage production in 9.5 hours, but most try to keep it within 10 hours. Gaining half an hour of time comes at the cost of enormous effort, people become squeezed like lemons, they only have the strength to get to bed. Yes, and the factory management can increase output for the Stakhanovites, forcing others to work the same way. Everyone is well aware of this, so they try to fit into typical norms - only sometimes, in connection with some celebrations, the teams can speed up.

It is curious that it is customary here to celebrate workers’ birthdays or other events. The dining room has separate rooms with round tables and the ability to seat one team. Occupying such a room costs nothing, the same food is served as for everyone, but people can celebrate something of their own in an intimate setting. In some ways, this reminds me of everyday life in the army, where your unit becomes everything to you - exactly the same role as a brigade in a Chinese factory - it should become a home for the worker.

Moving from one team to another is possible, sometimes it happens, but this is not encouraged - it’s easier to work with those you know well. The foreman is not a white-handed worker at all; he works on an equal basis with the others, although he has some privileges. It is interesting that the foreman must master more operations in order to train newcomers if no one else can do it.

A Chinese factory is a sweatshop where workers work their butts off. In the morning they don't have time for breakfast, so at 11 o'clock there is what is called lunch. In fact, for most workers, it is the first meal of the day. The second meal occurs after 3-4 o'clock in the afternoon, and the ritual of removing workers from the workshop is repeated.

The foreman leads everyone through a metal detector, and workers can also be searched on special pedestals in search of parts that they might have removed. From the point of view of theft, each factory strives to protect itself and creates conditions under which it is impossible or extremely difficult to remove anything. At some factories, a paranoid level of secrecy is introduced, when not only players, phones or anything else are prohibited inside the production, but the finished products are locked in opaque boxes, which are moved to other workshops.

There is a little secret with which you can determine how serious measures are taken at the factory to ensure the safety of production and what happens in it. All you have to do is look at whether the girls behind the assembly line have headphones. The presence of your own players clearly indicates that it is possible to bring something of your own and take it back. As a rule, in most industries this is not possible.

Let's go back to the standard Chinese worker food. The two meals that occur in the factory are almost all the food a worker consumes during the day. On the territory of the factory there is a small store with a very modest selection of cookies, sweets and other nonsense to kill the worm. The diet is not rich in variety, and if you look into a dorm room, you will find foods such as tea, concentrated juices, soda, cookies and chocolate. Families can cook food, but they do this almost exclusively because of the children, who do not eat in the factory canteen.

The scarcity of food ten years ago was fantastic; I’m not sure that’s how they fed in the concentration camps. Some factories amazed me by the lack of not just a balanced diet, it was a cup of rice and some vegetables with tea. This spectacle always impressed the Europeans, but did not touch the Chinese themselves at all - they explained this by the fact that in the villages the food of their workers was even more meager. There is no reason not to believe these people, I think that’s how it all happened. But even then, there were no emaciated people at the enterprises, those who gave the impression of being sick or infirm. It is possible that the reason for this lies in the Chinese labor organization - as soon as a worker stops fulfilling his quota, he is abandoned and he is forced to leave the factory. A rough but extremely effective system that is focused only on results. There is no talk of any social protection for workers that would allow them to be paid if their work deteriorates. The most a Chinese worker can expect is payments from production if he becomes disabled due to the fault of the factory. The size of such payments is very small and cannot in any way cover the lack of work or provide a decent standard of living.

Another interesting question is the size of pensions in China and why rural residents are so willing to go to factories. The explanation should be sought in the fact that in China there are no pensions for peasants and rural residents, there are none at all. Government officials have a pension; the obligatory condition is to work for at least 15 years. The law also states that in enterprises, including private ones, employees must receive a pension upon reaching a certain length of service. The size of this pension ranges from 750 to 1200 yuan (3,800-6,000 rubles). As a rule, it is very difficult to fulfill all the conditions for receiving a pension. But this is an additional incentive to connect your life with the factory, since the pension guarantees life in old age. Historically, in China, parents relied on their children to support them in old age—the more children, the better off the parents were. The state program “one family – one child” has created a time bomb under this concept; parents of children born since 1980 can no longer count on support - one child is not able to feed two adults. The alternative is to work for the state, which, like a vacuum cleaner, takes away the most gifted and capable children, or, in the absence of education, to go to factories. This is state regulation of the economy, which de facto creates and enlarges classes - employees and workers.

Sometimes I come across reports about how Chinese workers live, or discussions about the difficult conditions of their work and also life. Some Western publications call this slave labor, which, of course, is not. But the fact that in China the state has created all the conditions for keeping the country’s residents busy is beyond doubt. The country is segregated based on the quality of people, and those who do not want to work have no place in this social structure - most people have to work to provide food for themselves. A lot and hard.

The working class in China is not privileged; on the contrary, they are the people on whose shoulders the economic miracle was built, and they are one of its constituent parts. Cheap labor of workers, multiplied by long working hours, gigantic output and low wages, create the economy of this fairy tale.

Conveyor - Japanese production version

Each factory strives for greater production efficiency; we are not talking about a multiple increase in product yield, but about percentages. Managers running factories readily and quickly adapt innovations that occur in production, especially if they are low-cost.

Typically, the conveyor on which the phone is assembled is a straight line with assembly tables. On each such table a certain operation is performed - first the board is inserted, then other parts are mounted, and so on. At the end of the conveyor there is an initial inspection of the resulting product or semi-finished product; at certain stages there is a quality check (both instrumental and visual). In Europe, in such factories you can see chairs and low tables, adapted for sitting people. In Asia, all production, or almost all, is for standing people (can you imagine 10 hours on your feet, almost in one position and at a narrow table? This explains the fatigue of people after a shift). The choice in favor of people standing during production is explained by physiology - pressure does not drop, concentration on details is higher and longer. The payback for this is more time for rest and sleep. This is beneficial for factories because workers do not have time to walk or do anything else; they either sleep or work.

At the Oppo factory they used a slightly different type of conveyor; it was placed not in one line, but in the letter P. This innovation was used in Japan about a year ago, as they say, this option allows you to save space and speed up work by the same percentage. Workers stand on the inside of the letter P and pass workpieces to each other.

The Oppo factory employs 1,700 people during the day shift and has 40 conveyors where phones are assembled. The plant is capable of producing up to 50,000 devices per day, but the actual production volume is slightly less; it is regulated by the night shift, which is not so numerous.

The conveyors described above are typical for any plant, whether it is located in China or another part of the world. In fact, we can say that most of the devices are assembled by hand, and this applies equally to both Oppo phones and the Apple iPhone coming out of Foxconn factories. The share of manual labor in each device remains maximum, and the idea of ​​ordinary people that all this is assembled by robots is as far from the truth as the number of such productions (they exist, but almost never produce goods for the mass market, the cost is too high, cheaper to use labor).

Full-cycle manufacturing also has its own SMT lines, where boards for phones are assembled. Almost always, when they want to talk about how modern and innovative production is, they show a picture of an SMT line on which machines lined up in a row string small parts onto a board, picking them up from reels. Robots skillfully and quickly assemble boards, which then undergo primary quality control.

The cost of one SMT line for the production of boards for phones is about 10-12 million dollars. There are five such lines at the Oppo factory, and it is planned to purchase two new ones with improved equipment. In fact, for each production, the maximum production volume depends not only on the number of workers and assembly lines, but on the number of SMT lines. Usually the ratio is 1 to 5, that is, five conveyors with workers are opened for one SMT line. This clearly shows the difference in performance between machines and humans.

The economics of production and conveyors are approximately the same for all companies, that is, here we can say that the equipment, the cost of labor and the thoroughness of intermediate testing at all stages of assembly differ. But the main difference in price between different factories lies in other aspects of the work, which we will talk about.

Testing of components and finished products

If an experienced eye can see a lot of things on the shop floor, evaluate the quality of work organization, and roughly estimate the cost of the product, then it will not be able to identify the main thing - how good or bad the final product is. Quality control is responsible for this, and it is not concentrated in the production premises, it is a separate laboratory. In factories where quality plays a major role, there are two laboratories - one tests its own, finished product, and the second checks all purchased components plus reviews components from new suppliers. In the case of Oppo, there are both laboratories. There were models at the test stands that have not yet been officially announced, so I won’t be able to show you all the devices and machines for testing. But I’ll tell you in general terms what happens behind the walls of these premises. Let's start with the component testing laboratory.

Each factory independently purchases many components - from plastic and screws to stickers for phone screens, displays, and material for printed circuit boards. To assemble one phone, two hundred items are required, and the work and quality of the final product can directly depend on any of the components. Therefore, input quality control is very important, and it starts with the simplest tests - the weight and size of the components. The supplier has specifications according to which it produces, for example, screws. They must be a certain size, weight and color. All this is checked for each batch that is delivered to the plant - here there is a random check. If the supplier is new or the component has never been supplied before, then the test is carried out on all possible machines - resistance to aggressive environments, humidity, strength characteristics, and so on. Whether the component passes these tests or not determines whether the factory will buy it or not. Often, components from several companies are tested simultaneously and the best are selected.

In the photo below you can see how the oleophobic coating of the display is tested in the laboratory by a drop of liquid placed on it.

This laboratory has X-ray machines to detect hidden defects in small parts, circuit boards, and so on. That is, this is full-fledged quality control of all components. Accessories, such as headphones, are checked in exactly the same way. After testing, they are cut so that they do not accidentally end up in manufactured products; weighty bags with cut off ears and connectors can be found in different places.

There is a separate room with test tables for cameras, modules are tested here - even before they are installed in phones, you can also check the final devices and how the software works.

The laboratory looks shabby, it is not brand new, which speaks better than any words that life is in full swing in it and work is constantly going on. This is one of the most interesting places in the factory. As a rule, outsiders are not allowed into these laboratories, since the equipment does not make a stunning impression, moreover, it is very difficult to explain its wear and tear, and such explanations can be perceived as excuses.

Several times I was unlucky to get on press tours of factories, where we were taken to specially created production facilities, in particular, we were shown perfectly clean laboratories of incoming quality. When asking how long ago the laboratory was built, I found the answers very funny - a year ago, several years. Such laboratories cannot always be tidy - they are clean, but wear and tear on the equipment and scratches on it occur due to the fact that it is used. But if they don’t use it, then none of this exists.

In the testing laboratory, where finished phones are tested, there are several rooms, each of which is designed to test devices under different conditions. I’ll start with a climate laboratory in which large metal cabinets are installed - inside each such cabinet a certain temperature and humidity can be created, this is an imitation of different climatic zones.

Phones can be inside either on or off. A separate installation is responsible for the artificial aging of materials; this is, perhaps, the place from which they are trying to quickly remove it, since they do not want to give away their know-how. By and large, an aging installation is a combination of machines that simulate climatic conditions - ultraviolet light and possibly something else are usually added to humidity and temperature. It is the testing methodology that is the secret - it is important to achieve a real aging effect in the shortest possible time, which allows you to change the technological process and avoid problems in the future. European engineers treat such installations as shamanism and condemn them, quite sensibly noting that they are not certified, are a product tied exclusively to Chinese realities and do not have a 100% guaranteed result. There is no harm from them, but a certain benefit can still be traced. I wouldn't be surprised if the Chinese eventually create something through trial and error that will work and guarantee results. For now, we can perceive this direction as promising, but by no means the main one.

For phones with IP/IPX protection level, there are cameras in which the devices are filled with water from different angles (the most interesting thing about such cameras is the wipers that clear the glass of water from the inside so that you can see the device).

Household use and durability of the devices are tested on other devices. The mechanical strength of the screen is tested by metal balls that fall onto it from a certain height. I didn’t risk putting my phone under this torture machine, although I understood that it had passed exactly the same tests and should withstand everything here too. Psychologically, this is the most win-win test that the manufacturer can demonstrate - a heavy metal ball falls on the screen and leaves no traces on it.

The machine works to abrade the surface with jeans on the handles, a phone in the pocket, and the fabric rubs against the body. About several hundred thousand times. In general, when I talk about strength or abrasion tests, you need to understand that they go through 100-300 thousand repetitions. This is an automatic device that checks the number of clicks on the screen in different places, and a device that takes a photograph of a magazine page, immediately erases the picture and takes the photograph again - this is how the camera’s life is checked.

In another machine, the phone is clamped in two claws, and they begin to twist it in different directions, trying to bend it. Next to it, the machine polishes the surface of the plastic using different materials – cloth, denim, leather and others. This is also a surface abrasion test under different conditions.

Measured claps are heard from another row, about ten phones are lifted 10 centimeters on suction cups and then dropped onto the metal surface of the machine. Then the suction cups lower again, and everything repeats. This happens a hundred thousand times, and the phone must withstand all the tests.

There is a separate radio laboratory where they check how the phone's radio module works. An artificial hand costing 2,500 euros holds the phone, and inside a sealed chamber it is tested for all frequencies. There are two such cameras at the Oppo factory; nameless Chinese manufacturers or small factories don’t have them at all; it’s too expensive.

A short afterword, or to be continued

If in the first part of the report from China we talked about the place of factories in the state, what they are, how propaganda works in production, then in this part we were able to look behind the scenes of production and see production workshops, as well as laboratories using an example one, quite good factory. Behind the scenes there was a story about the highest paid employees of the factory, the role of design and why there are so many different shells for Android and what kind of human factories do this in China. This will be the subject of the third part of the report. Don't miss it. I also hope that after this material the question of why one device costs one hundred dollars and another three hundred, and whether this is only a payment for the brand, will not arise. This report shows what affects the cost of the final product and what such thorough testing brings, besides increasing the price.

Russian manufacturers of communication equipment, network, fiber optic, telecommunications equipment. Big brands and new brands. Catalog 2019, official websites, addresses, contacts and prices of manufacturers. Suppliers of our own products are reliable partners. Become a dealer, order a price list!

Manufacturers of communication equipment and telephone equipment in Russia cannot yet compete equally with foreign ones, although their products are much better adapted to the Russian cable infrastructure.

A significant portion of the market is occupied by fiber-optic networks. For 2013 The production of optical cables increased from 7110 thousand km. up to 8366 thousand km. Russian factories of modern communication equipment develop, manufacture, implement and service products independently.

Among the first is ZAO NPK ROTEK, specializing in the creation and implementation of multi-service, geographically distributed communication and television and radio broadcasting networks. The plant produces over 50 models of equipment and occupies a leading position in Russia and the neighboring countries.

Zelax is a Russian developer and manufacturer, has been cooperating for many years with the largest enterprises in strategic sectors of the Russian economy and government agencies. Russian customers of Zelax, for whom equipment reliability is paramount: FSB, Ministry of Internal Affairs, Ministry of Emergency Situations, Ministry of Defense, FSO, Gazprom, Russian Railways, Rostelecom, AvtoVAZ. The products are certified and comply with GOST.

The First Russian Telephone Company has been working with telecommunications in Russia and the CIS countries for 14 years, from idea to implementation, implementing independently. The company develops and produces solutions for communications and telecommunications, which are used in Ukraine, Kyrgyzstan, Kazakhstan, and Armenia.

Broadband radio access systems are another area of ​​the market where Russian developers have achieved success: 60% of wireless networks in the country use routers from the Russian manufacturer InfiNet Wireless.

If you are interested in the products of manufacturing companies presented in the catalog, you can use the contacts provided to contact the factory directly, become a dealer or wholesale partner in your city.

TOPIC No. 6

Telephone sets

Lesson No. 1

Purpose, classification, characteristics and parameters of telephone sets

QUESTIONS:

Purpose and classification of telephone sets.

Main parameters and characteristics of the TA.

First study question

Purpose and classification of telephone sets

Telephone apparatus (TA) is designed for transmitting and receiving called and spoken signals and contains called, spoken and switching devices.

Called devices include call making and dialing devices (inductor, dialer and call receivers (bells, acoustic signaling devices)).

Conversational devices include a microphone and telephone, mounted handsets, and a telephone transformer.

In some types of devices, speaking devices are supplemented with amplification devices.

A telephone transformer is used to create a conversational circuit for a telephone set, match its output impedance with the input impedance of the line, and also to separate the power circuits of the microphone and telephone.

Switching devices: lever contact switches and in some types of special devices, for example, for operational and technological communication of railway transport (buttons and microphone valves).

TA classification:

1) By purpose:

General use, these include ordinary TA

Special-purpose devices for operational-technological communication (OTC), field, etc.

2) According to the method of power supply to microphones:

TA local battery system (MB);

Central battery (CB);

Battery-free.

3) By type of station in which they are intended to be included:

Manual telephone exchanges

Automatic telephone exchanges

4) By the method of switching on conversational devices:

SLT with a constant circuit for switching on speaking devices (Fig. 6.1.1a), which does not change during the transition from speech transmission to reception and back (public SLTs used on local telephone networks).

Fig.6.1.1. Schemes for connecting conversational devices to TA

SLTs with a variable circuit for switching on speaking devices (Fig. 6.1.1b) are characterized by the fact that when transmitting speech, the microphone circuit BM is connected to the device circuit, and when receiving, the telephone circuit BF is connected. These switchings are carried out by the valve (push-to-talk) SP - this is used in operational-technological communication (OTC).

5) The method of switching on the calling devices differs:

a) with the inclusion of calling devices (VP) in the subscriber line L (Fig. 6.1.2a), while the VPs are separated from speaking devices (PR) by the contacts of the lever switch SA (used for telephone communication of the MB and CB systems).

Fig.6.1.1. Schemes for connecting calling and conversational devices to the telephone

b) with the organization of the VP circuit using the PV call receiver when a call signal arrives (used in the OTS, as well as in the SLT with an acoustic tone call).

6) By type of calls received Galov:

With an alternating current call with a frequency of 25-50 Hz. Most common for general use and used on CPU systems

With DC call. Used in MB systems, used in OTS

7) By design:

Stationary (desktop, wall-mounted, combined)

Portable

Telephone sets can be classified depending on their use of a particular type of communication (Fig. 6.1.3).

Fig.6.1.3. Classification of TA by type of communication used

Circuit-switched networks primarily use the simplest analog telephones, in which speech signals are received and transmitted in analog form. ISDN digital telephones, which receive and transmit voice signals in digital form, are also used on such networks. In packet-switched networks, users have IP phones installed, which also provide information transmission in digital form. The devices considered are characterized by the fact that they are installed in the place where the subscriber line ends. In mobile communication networks, telephones can change location within the network coverage and can be used while on the move. This became possible due to the fact that instead of a wired subscriber line, a radio channel appeared here.

The telephone must be powered from a DC source for various devices: microphone, amplifiers, microcircuits. Telephones can be powered by a central battery system (CB) or local battery (MB).

In the central bank power system, telephone sets are powered from a common source located at the telephone exchange and called the central battery. At a telephone exchange, the common DC source has a voltage of 48 V (foreign standard) or 60 V (Russian standard). In a centrally powered system, the supply voltage is also used to send a call from an analog SLT to the PBX. The power supply system of the central bank is used for all analog SLTs and for most digital ISDN SLTs. In a packet switched network, IP phones can also receive power from the network node in which they are connected.