RU32655U1 - Switching system - Google Patents

Description

The proposal relates to telecommunication technologies that use combined means of switching channels and packet data transmission for cost-effective organization of communication while improving the quality of customer service and providing them with a wide range of additional services.

Numerous sources of information are known dedicated to telecommunication technologies of IP-telephony based on packet information transmission and Internet access. Any prestigious Publishing House does not pass by this currently most fashionable topic. In any professional book you can find at least 50 references to well-known publications. An example is the book IP Telephony, A.V. ROSLYAKOV, M.Yu. Samsonov and I.V. Shibaeva, ECO TRENDS Publishing House, Moscow, 2001, in particular, Section 1.5, Fig. 1.8, p. 20. Magazines, such as, for example, “Technologies and means of communication from number to number publish various options for solving the above problem, see, for example,“ Technologies and means of communication No. 5, 2002, the article “A new approach to an urgent problem, p.24.

All this testifies to the fact that “the old switching systems, on the principles of which the public switched telephone network has been built over the decades of PSTN, are being replaced by“ new switching systems compatible with PSTN. And the main criterion for choosing such switching systems is economic, of course, with guarantees of the quality of communication required by network operators and the possibility of providing subscribers with a wide range of additional services. A technical solution that meets these requirements is the subject of this application.

In all of these well-known sources of information, such basic elements as “gateway,“ router, “server, etc. those. the same basic elements that we will have to use when describing our application (though with other connections between them and their other “software filling”).

The terminal-transit modules can also be selected as an analogy, as described in the brochures of the Electronic Telephone Exchange “Elcom (Certificate SSE, No. OS / 1-G-95, SZI No. 77 dated January 30, 1997), as well as in the Integrated Electronic Automatic Telephone Exchange (IEATS) ), certificate - II quarter. 1997 Integrated Communication Networks OJSC, 13184, Moscow, ul. B. Tatarskaya 38.

These analogs have in common the presence of a group part that provides circuit switching, to which subscriber terminals can be connected at the input, and at the output, the inputs of transmission systems.

The latest development of the aforementioned company Elkotom (certificates of 2001), which demonstrated its achievements at the Norwegom-2003 exhibition of communication systems and telecommunications, held in St. Petersburg from February 25 to 28, 2003, is the digital switching system SCK Elkom, built on the basis of universal modular solution “Elkom. The advertising booklet provides a fairly detailed technical description. This booklet was available to an indefinite number of visitors to Norvek 2003 and was published on the initiative of the Russian Telephone Company, Russia, 192298, St. Petersburg, Garage passage, 1, tel. 380-09-99, 380-09-88,

tel / fax 380-09-90, www, itci.spb.ra, acbnin @ rtcLsi) b, m.

All of the above known devices are selected as analogues.

As the closest analogue - i.e. We also selected the prototype switching system described in the book: Kutashov P.D. and others. "City coordinate automatic telephone exchanges of the type ATSK, - M, communication, 1970, chapter 1, p. 418 (various options for intra-office and inter-office communications), chapter 4, p. 50-56 (connection establishment processes) and chapter 8, p. .228-270 (various types of subscriber kits, cord kits, shngurov kits for switching on payphones and sets of trunk lines).

In Appendix 1 in Fig. 1 shows a structural diagram of a known switching system - prototype.

ATSK-type switching systems were selected as a prototype for the reasons that they (together with ATSKU-type exchanges) are, firstly, most common on Russian telephone networks (their implementation is more than 50%), and secondly, they contain the largest number of elements and connections between them, common with the green switching system.

Due to the fact that to date, most of the switching systems installed by telecom operators such as ATSK, ATSKU have partially or almost completely exhausted their resources (after all, their active implementation began in the 60s of the last century), as well as due to the fact that these switching systems are currently morally obsolete. 1S, telecom operators are faced with the task of either their first replacement with modern electronic systems (which is not realistic for economic reasons), or their radical modernization.

It seems that the claimed switching system in the best way meets the requirements of such modernization both from an economic point of view, and from the point of view of the possibility of providing subscribers with a wide range of modern communication services (IP-telephony, Internet access, etc., etc. .).

system, only coordinate switching systems. To expand the functionality of the system and provide subscribers with new services, electronic switching systems in which such services are not available can be upgraded.

But we repeat, the most important for improving communication systems in Russia is the radical modernization of electromechanical switching systems, the main representative of which is the coordinate switching system. Hence the relevance of this application.

So, we consider the main disadvantages of the known switching system, selected as a prototype.

The disadvantages of the prototype include:

- a large amount of equipment due to the fact that the group part of the known switching system (both coordinate - prototype, and electronic - analog) is based on a channel switch,

-conditioned by this relatively high cost of the switching system,

-lack of modern services that can be provided to subscribers.

Note: some services, such as HanpHMq), such as access to the Internet, in a telephone network based on the mentioned switching systems, can still be made available to subscribers, however, their implementation requires the use of the resources of the entire (collectively) telephone network with the ensuing from this 5T circumstances improving communication quality for all telephone network subscribers (the telephone load created by subscribers - Internet users significantly exceeds the telephone load created by ordinary subscribers, but the telephone network is not calculated tana to skip such a total telephone load).

- the impossibility or economic inexpediency of introducing into the switching system equipment to provide these services without compromising the quality of customer service,

-complexity and the resulting high costs of organizing centralized technical operation and network management, due to the fact that when developing electromechanical switching systems, these tasks were not posed and, of course, were not solved. The solution to these problems can only be achieved by using high-cost hardware-software hardware.

The elimination of these drawbacks was possible due to the complete replacement of the group part of the switching system with circuit switching (analogues and prototype) by the group part of the switching system with packet switching and pairing it with the equipment of subscriber units of outgoing and incoming communication using matching devices (newly introduced into the claimed switching system elements and the relationships between them will be given below).

The inventive switching system eliminates the above disadvantages of the switching system of the prototype.

The inventive switching system provides:

-significant reduction in the volume of equipment switching system,

-decrease in the cost of the switching system,

- providing subscribers with a wide range of modern high-tech communication services,

-convenience and substantial economic feasibility of organizing centralized technical operation and network management.

The purpose of the proposed switching system is to simplify its implementation and the volume of equipment, as well as reduce its cost while improving the quality of customer service (or, in some cases, maintaining the existing quality) and expanding the range of additional communication services provided to subscribers, especially with a radical modernization of existing systems commutation.

The aim of the proposed switching system is also to ensure that the "old, modernized switching systems (more precisely, the equipment of the" old systems that will remain in operation after a radical modernization) continues to operate in channel switching mode both for outgoing communication and for incoming communication , and the new equipment with which this modernization is carried out would work in the packet switching mode (it is this new equipment that guarantees the above-mentioned intellectual leap).

So, the claimed switching system, like the well-known switching system, selected as a prototype, contains a subscriber unit with a group of subscriber sets and a group switching subscriber device, the inputs of the subscriber sets of the group of subscriber sets on subscriber lines are connected to the subscriber telephone settings, and their outputs are connected to the first inputs of the group switching subscriber device, while the first outputs of the group switching subscriber device are connected to the first group of outputs of the group part of the switching system is connected to the second inputs of the group switching subscriber device, the second outputs of which are connected to the said group of subscriber units sets, while the group part of the switching system has second inputs associated with transmission systems in directions from other comm , Gravitational systems.

These goals of the proposed communication network in accordance with paragraphs 1-6 of the formula were achieved due to the fact that the group part of the switching system is made in the form of a unified module for packet data transmission, containing hardware and software, which include a signaling gateway (SG) with a protocol Session Initialization Protocol (SIP) or a modification of this protocol, media gateway (MG), local area network (LAN) switch - Ethernet switch, asynchronous multiplexer demultiplexer, and modulators - demod the headers and / or the first group of matching devices of the transmission systems, as well as the second group of matching devices of the outgoing communication and the third group of matching devices of the incoming communication, the signal gateway SG and the media gateway MG being connected to each other by a bi-directional control bus, the LAN switch is connected to the signaling gateway SG , media gateway MG and inputs for connecting subscriber terminals, the output of the SG signaling gateway is connected via a bi-directional PCI bus with the input of an asynchronous multiplexer - demultiplexer, and a signaling via a bi-directional bus communications with the first inputs / outputs of modulators - demodulators and / or the first group of matching devices for transmission systems, the second group of matching devices for outgoing communication and the third group of matching devices for incoming communication, the second inputs / outputs of which are connected to the outputs of the asynchronous multiplexer - demultiplexer, and the third inputs / the outputs of which are connected with the information output / input of the MG media gateway, while the fourth and fifth outputs / inputs of modulators-demodulators and / or the first group of matching devices of transmission systems via Keys to the inputs of transmission systems, the sixth input / output matching circuits of the second group outgoing communications associated with said first output of the switching device of the subscriber group, seventh outputs / inputs of a third group of terminating devices incoming communication associated with said second input of the switching device of the subscriber group.

In addition, these goals can be achieved due to the fact that the aforementioned sixth inputs / outputs of the second group of outgoing communication devices are connected to the aforementioned first outputs of a group subscriber switching device through electromechanical cord outgoing sets or equipment of electromechanical switching systems similar to cord sets, and the seventh the outputs / inputs of the third group of matching devices of the incoming communication are connected with the mentioned second inputs of the group tskogo electromechanical switching device through Cord incoming kits or similar pull cord sets equipment electromechanical switching systems.

(Proxy-Server) of incoming connections - communication sessions, the bidirectional input / output of which is connected to a LAN switch - Ethernet switch.

In addition, these goals can be achieved due to the fact that smart terminals with SIP protocol, such as SIP - telephone terminal or SIP - computer terminal, are connected to the LAN - Ethernet switch.

The achievement of these goals is also achieved due to the fact that a router has been introduced into the unified module, the first bidirectional input / output of which is connected to the LAN switch - Ethernet switch, and the second bidirectional input / output of which is connected to the Internet.

These goals are also achieved by the fact that a gateway is introduced into the unified module, the first bidirectional input / output of which is connected to the LAN switch - Ethernet switch, and the second bidirectional input / output of which is connected to the public telephone network - PSTN network.

In FIG. 1 shows a structural diagram of the inventive switching system, common with the structural diagram of the system is a prototype.

In FIG. 2 shows the disclosure of the group part of the switching system, which (group part) is built on the principle of packet transmission.

In FIG. Figure 3 shows the elements and connections of a group switching subscriber device with a unified packet transmission module.

In FIG. Figure 4-7 shows a structural diagram of a unified packet transmission module, expanded with new functional elements, respectively - a forwarding module (Proxy Server), SIP terminals, a router (for communication with the Internet) and a gateway (for communication with the PSTN network).

Appendix 1 shows the structural diagram of the switching system - the prototype.

Appendix 2 shows an example of the implementation of the first matching devices for matching the main equipment nodes of the claimed switching system with three-wire physical connecting lines of communication directions to (from) other (other) switching (switching) systems (description, functional and circuit diagram - on 3 sheets).

Note: implements {I agree on devices of the second and third groups of analogue "on (taking into account the specifics of constructing different types of electromechanical switching systems, i.e. taking into account the specifics of the internal interfaces of these switching systems and the number of actuators - physical - between the equipment of electromechanical switching systems and matching devices of the second and third groups).

In FIG. 1 shows a switching system containing subscriber unit 1 (this unit provides the establishment of both outgoing and incoming communications) with a group of 2 subscriber sets 3 and 4 (in reality, the number of subscriber sets corresponds to the number of subscribers connected to the switching system, but not to clutter the figure , in Fig. 1 only two of them are shown) and a group switching subscriber device 5. Inputs (outputs - see below) 6, 7 subscriber sets 3, 4, respectively, are associated with subscriber telephone installations kami 8, 9 on subscriber lines 10 and 11. The outputs (inputs - see below) of subscriber sets 3 and 4 are connected to the first inputs 12 (for organizing outgoing communications) of group switching device 5 and with second outputs 13 (for organizing incoming communications) of the same device 5. In FIG. 1 (for convenience of consideration) it is shown that the output 14 of the subscriber set 4 is connected to the first input 12 of the device 5, and the input 15 of the subscriber set 3 is connected to the second output

13 devices 5 (in reality, each of the subscriber sets has a high code

14 and input 15, but in FIG. 1, these outputs and inputs, for the convenience of consideration, are shown separately for subscriber sets 3 and 4). In electronic switching systems, such a construction of subscriber sets is possible in which output 14 and input 15 are combined into one bi-directional input / output (such a construction of subscriber sets so as not to clutter Fig. 1 and the description of the application is not shown).

The group switching subscriber device 5 of the electromechanical switching systems (see prototype) has first inputs 16 and second inputs 17 (in Fig. 1 only one output 16 and one input 17 are shown, although in reality there is a group of outputs and a group of inputs, the number of which is approximately 10 times less (depending on the specific project of the switching system) the number of subscriber sets, because at the level of subscriber unit 1, the outgoing connection is subject to compression of the telephone load, and for incoming communication - its expansion).

In a group switching subscriber device 5 of electronic switching systems, the outputs 16 and inputs 17 can be combined into bidirectional inputs / outputs implemented as a standard digital stream E1 (in Fig. 1, so as not to clutter up Fig. 1 and the description of the application are not shown).

The first outputs 16 of the group switching subscriber unit 5 are connected to the first inputs 18 of the group part 19 of the switching system (Fig. 1 shows that one input, although in real systems there is a group of such inputs). The first group of outputs 20 of the group part 19 of the switching system is connected with transmission systems in the directions to other switching systems (these transmission systems are not shown in FIG. 1 so as not to clutter the figure). The second group of outputs 21 of the group part 19 of the switching system is connected to the second inputs 17 of the group switching subscriber device 5 (in Fig. 1 only one output 20 from the first group of outputs and only one output 21 from the second group of outputs is shown, so as not to clutter the figure).

The group part 19 of the switching system has second inputs 22 connected to the transmission system in directions from other switching systems (Fig. 1 shows only one such second input 21 of the group of inputs so as not to clutter the figure). In principle, with the digital implementation of the group part 19 of the switching system, its inputs and outputs can be bi-directional.

In FIG. 1 elements 23 - 25 are not shown, their numbers are reserved.

In FIG. 2 shows the group part 19 of the switching system, made in the form of a unified module of a packet information system containing hardware and software. These hardware and software tools include 26 SG signaling gateway with Session Initialization Protocol (SIP) 27 or a modification of this protocol, 28 MG media gateway, local area network (LAN) switch 29 - Ethernet switch, asynchronous multiplexer - demultiplexer 30 and modulators demodulators (M / D /) (and / or the first group of matching devices (CS) transmission systems) 31 and 32.

The SG signaling gateway 26 and the MO media gateway 28 are interconnected by a bi-directional control bus 33.

The LAN switch 29 (Ethernet switch) is connected to the signal gateway 26 SG bus 34 (bidirectional), and with the media gateway 28 MG - bus 35 (bidirectional).

The unified packet transmission module 19, in addition to the first group of matching devices 31 and 32, also includes a second group of matching devices (SU) 36 for outgoing communication and a third group of matching devices (SU) 37 for incoming communication. The second group of matching devices 36 is connected to the subscriber unit 38 of the outgoing communication, and the third group of matching devices 37 is connected to the subscriber unit 39 of the incoming communication.

Note: 1) in FIG. 2 (and further on in Figs. 4-7, see below) is shown so as not to clutter up the drawing, only one matching device (CS) 36 from the second group of matching devices and only one matching device (CS) 37 from the third group of matching devices ,

2) the outgoing communication subscriber unit 38 and the incoming SVEZI subscriber unit 39 form, in aggregate, the outgoing and incoming subscriber unit 1 shown in FIG. 1. The division of block 1 into two bls is artificial, but it is convenient for understanding the essence of this application.

pa - demultiplexer 30. In addition, the signaling gateway 26 SG is connected via a bi-directional signaling bus 46 to the first inputs / outputs 47 and 48 of modulators-demodulators (and / or the first group of matching devices of the transmission systems) 31 and 32, respectively.

The second inputs / outputs 49 and 50 of the elements 31 and 32 are connected to the outputs 51 and 52 of the asynchronous multiplexer - demultiplexer 30. The third inputs / outputs 53 and 54 of the elements 31 and 32 are connected to the information output / input 55 of the media gateway 28 MG

The fourth and fifth outputs / inputs 57 and 58 of modulators of demodulators (and / or the first group of matching devices of transmission systems) 31, 32 are connected, respectively, to the mentioned inputs 59, 60 of transmission systems 61, 62 (existing), which (inputs 59, 60) performed bidirectional.

Notes: 1) in FIG. 2, 4 - 7, only two modulators are shown — a demodulator (and / or matching devices) 31 and 32, and only two signal transmission systems 61, 62, which (systems 61 and 62) are part of the signal transmission medium 63. In real conditions, the number of demodulator modulators (and / or matching devices) and the number of transmission systems is determined by the specific configuration of the modernized communication network.

2) it should be noted that if the transmission system 61, 62 has good parameters and can be used for data transfer, then modulators-demodulators are connected to it, and if it has poor parameters and high-quality data transfer cannot be organized, then matching devices that are used in the same way as they would be used for switching channels.

The signal transmission systems 61, 62 are connected by their outputs to the channels of the transmission systems to other stations and transit nodes (not shown in FIGS. 2-7).

It should be noted that one hundred signal gateway 26 SG via a bi-directional signaling bus 46 is connected, in addition to the above, with the inputs / outputs 66 and 67 of the second group of matching outgoing communication devices 36 and the third group of matching incoming communication devices 37, respectively.

The output 55 of the media gateway 28 is connected, in addition to the above, with the inputs / outputs 68 and 69 of the second group of matching devices 36 for outgoing communication and the third group of matching devices 37 for incoming communication, respectively.

The output 70 of the asynchronous multiplexer - demultiplexer 30 is connected to the input 71 of the matching device 36 outgoing communication of the second group of matching devices. The output 72 of the asynchronous multiplexer - demtlexer 30 is connected to the input 73 of the matching device 37 of the incoming communication of the third fuppa matching devices.

devices of all three groups. Such a construction (within the framework of this application) is due to the desire to facilitate understanding of the essence of the proposed proposal.

Obviously, with a large number of matching devices, this solution is technically cumbersome. In this case, it is natural to organize at the output of an asynchronous multiplexer - demultiplexer 30 instead of the above-mentioned individual outputs of one address multi-wire (10 - 12 wires) bus. In this case, an address decoder should be entered into each matching device, the setting of which should be individual for each matching device. The address bus in FIG. 2, 4 - 7 is not shown and is not mentioned in the formula. We ask the expert to treat this note as a variant of a technical solution equivalent to the declared technical solution.

The outputs 74 of the third group of matching devices 37 incoming communication is connected to the inputs 75 of the subscriber unit 39 incoming communication.

Note: in FIG. 2 shows one matching device 36 and 37 from the second and third groups of matching devices so as not to clutter the figure and description of the application).

The inputs 76 of the second group of matching devices 36 for outgoing communication are connected with the outputs 77 of the subscriber unit ЗВ for outgoing communication.

In FIG. There are no 2 elements with numbers 40 - 42, numbers 40 - 42 are reserved.

In FIG. Figure 3 shows the elements and connections of a group switching subscriber device with a unified packet transmission module for electromechanical switching systems.

In FIG. Figure 3 shows that the first outputs 16 of the group switching subscriber device 5 of the electromechanical switching system (for example, automatic telephone exchanges of the type ATSK, ATSKU) are connected (when organizing outgoing communication) with the first inputs 18 of the group part of the switching system, i.e. with the inputs of 76 matching devices 36 outgoing communication of the second group of matching devices through electromechanical outgoing cord sets 78.

The second inputs 17 of the group switching subscriber device 5 of the electromechanical switching system (for example, PBX type ATSK, ATSKU) are connected (with incoming communication) with the outputs 21 of the second group of outputs of the group part 19 of the switching system, i.e. with the outputs of 74 matching devices 37 incoming communication of the third matching devices through electromechanical incoming cord sets 79.

Note: instead of outgoing patch sets 78 and / or instead of incoming cord sets 79 in electromechanical switching systems (different from ATSK, ATSKU), equipment similar to the mentioned outgoing and incoming cord sets can be used.

Note that the outgoing cord sets 78 are connected with their inputs to device 5, and with their outputs - to device 19, while the incoming cord sets 79 with their inputs are connected to device 19, and with their outputs - to device 5.

In FIG. 4 is shown, in addition to FIG. 2, introduced in the unified module 19 server (module) forwarding (Proxy Server).

The forwarding server (module) 80 is connected to a LAN switch 29 - Ethernet switch via bus 81.

In FIG. 5 are shown, in addition to FIG. 2, 4, connected to the 29 LAN switch - Ethernet switch; intelligent subscriber installations - SIP terminals.

A telephone SIP terminal 82 (PSTN) and a computer SIP terminal 83 are connected to a LAN switch 29 via buses 85 and 86, respectively.

In FIG. 6 shows, in addition to FIG. 2, 4, 5, connecting a router to organize access to the Internet.

In FIG. 6 shows a router 87 connected to a LAN switch 29 via a bus 88.

In FIG. 7 shows, in addition to FIG. 2, 4, 5, 6, connecting a gateway to organize access to the PSTN network.

In FIG. 7 shows a gateway 89 connected to a LAN switch 29 via a bus 90.

Note: Forwarding server 80, routers 87 and gateway 89 have bidirectional inputs / outputs. Router 87 and gateway 89 are connected via bidirectional buses 88 n 90 to the 29 LAN switch with their inputs / outputs, and are connected to 91 Internet networks and 92 PSTN networks via their outputs / inputs. Consider the work of the switching systems proposed in the framework of this application.

First, note the following. A key role in the claimed technical solution is assigned to packet telephony solutions based on the SIP protocol.

Switching systems built on the basis of the proposed unified modules, unlike existing systems with circuit switching, are combined switching systems that operate both in channel switching mode and in packet switching mode.

Note: Speaking of “channel switching in the context of this application, we, to some extent, pay tribute to traditional terminology. shifting concepts. In fact, with the help of the GKSnal gateway SG n the copper copper MG, on the basis of which (using the SIP protocol) a switch of information packets was created, all 100% of the connections (and those connections (whose information should preserve the packet form, those connections for which in the future (within the framework of the claimed switching system) channel switching should be organized.In order to organize channels in the SG and MG gateways, a connection route is formed for each information packet with an accuracy of a specific line (channel) in the required direction occurrence connection and this marshrug maintained throughout compound (including while there is still no concept of "switching channels).

The original analog signal generated in the telephone installation of the subscriber is restored in matching devices 31, 32, 36 and 37 (this will be discussed below) and then transmitted in exactly the same way as was done in traditional switching systems with circuit switching.

And from what has been said it follows that within the framework of this application it would be advisable to replace the “channel switching” with the term “switching restored channels. The true channel communication is stored only in the subscriber unit 1 (38, 39) (in the tradicional sense of this concept). At the same time, the principal difference compared with existing switching systems is that the system is controlled by the SG signaling gateway. To the switching system on the basis of the proposed unified modules, both the terminals of the circuit switching networks (analog telephones) and the terminals of the packet switching networks (SIP telephones, computers) can be connected.

Outgoing, incoming, and also communication with subscribers using SIP telephones is carried out through a packet switching system using NGN protocols (Sigtran, Н.248, SIP) and speech compression technologies (G.723.1) implemented in the MG media gateway .

It should be noted right away that the implementation of the proposed control system in the proposed switching systems allows us to achieve a significant reduction in the cost of such a combined system (switching of both channels and packets), which is especially noticeable not only when modernizing urban electromechanical switching systems, but also when upgrading switching systems at the level of terminal stations, hub s-stations and central stations in the rural areas of the communication network.

The proposed technical solution is suitable for working with SIP protocol and RTP / RTCP packet transmission protocol via air lines 11 (for example, V-2-2), analog transmission systems (for example, KNK-12), digital transmission systems (PCM-15, IKM-30), as well as through physical two-wire and three-wire connecting lines (SL).

The proposed approach is not rigidly tied to existing analog and digital transmission systems, which opens up the possibility of developing a communication network in the case of modern transmission systems (for example, based on xDSL technology, hybrid and optical systems

access or even based on PLC technology for transmitting high-speed data through power lines).

So, let us consider the operation of the switching system shown in FIG. 1. The block diagram of the claimed switching system depicted in FIG. 1, coincides with the structural diagram of the switching system of the prototype.

For convenience, consider the process of establishing a regular telephone connection for in-house communication.

Suppose that the subscriber of telephone installation 9 picked up the handset. In this case, the loop of the subscriber line 11 will be closed and the busy signal will be received at the input 7 of the subscriber set 4. The subscriber set 4 is a part of 2 subscriber sets associated with the group switching subscriber device 5. The operation of the subscriber set 4 completely coincides with the work of the subscriber set of the switching system - the prototype. At the output 14 of the subscriber set 4, a signal appears that is fed to the input 12 of the group switching subscriber device 5. The operation of the specified device 5 also coincides with the work of a similar device of the switching system - the prototype. The device 5 is connected with its first outputs 16 to the first inputs of the group part 19 of the switching system.

Note: 1) in FIG. 1 only the first output 16 and only one first input 18 is shown, however, in real switching systems, there is a group of outputs 16 containing "n outputs and a group of inputs 18 containing" n inputs. The same applies equally to the second group of outputs 21. associated with the second inputs 17, which we will discuss below.

2) in FIG. 1 are not shown, for the sake of prejudice, outgoing cord sets, although it is known that electronic switching systems and electromechanical switching systems cannot work without such sets (this sets are connected between outputs 16 and inputs 18). The aforesaid applies equally to incoming cord sets, which are connected between outputs 21 and inputs 17, which we will discuss below.

3) in FIG. 1 also does not depict 1 dialers of dialing numbers of the called subscriber (for electromechanical switching systems, the number of the called subscriber is received and fixed in the subscriber registers, which are also not shown in Fig. 1, associated with cord sets).

So, after closing the loop of the subscriber line 11, the subscriber of the telephone installation 9 dials the number of the called subscriber, which is received and fixed in the equipment of the switching system. Then, by the number of the called subscriber, the group part 19 of the switching system establishes a connection. If the subscriber of the telephone installation 8 and the subscriber telephone installation 9 acted as the called subscriber, his number was dialed, then the connection

, (f

will be installed through the output 21 of the second group of outputs of the group part 19 of the switching system, through the incoming cord set (not shown in Fig. 1), through the second input 17 of the group switching subscriber unit 5, its output 13 to the input 15 of the subscriber set 3 and further, through its output 6 on the subscriber line 10 to the subscriber telephone installation 8.

When establishing an outgoing connection from the subscriber telephone installation 9 to the subscriber included in another switching system of the communication network (public telephone network PSTN), this outgoing connection is established (by the number of the called subscriber) through one of the outputs 20 of the first group of outputs of the group part 19 of the switching system .

Consider the operation of the proposed switching system depicted in FIG. 2. In FIG. 2 shows the disclosure of the main elements of the main part 19 of the switching system in accordance with this proposal, and shows 1 how (with the help of which particular elements and which connections) the main elements of the group part 19 are interfaced with that equipment of the old switching systems (electromechanical, quasi-electronic and electronic), which can be used (saved) during a radical modernization of these “old switching systems.

When establishing communication from subscribers included in the switching system of FIG. 2 (subscriber settings and subscriber lines in Fig. 2 are not shown, so as not to clutter up the drawing), the application from the subscriber (traditionally in the form of lifting the handset and closing the loop of the subscriber line) is received in the equipment of the switching system. Communication with the subscriber is carried out according to the "old method based on the" Z interface.

The application from the subscriber arrives through the subscriber unit 1 (38, 39) to the hardware-software means of packet information transmission — to the unified module 19 of packet information transmission, which instead of switching channels (which took place in the prototype) commutes information packets. As the packet information protocol, the SIP protocol (SIP-T) was used in conjunction with the RTP protocol (RTCP), which is currently one of the most progressive developments of leading data transfer companies.

It should be noted that the above-mentioned SIP protocol is proposed to be used not for its intended purpose: instead of access to the Internet (this is the main purpose), the SIP protocol is used to organize packet data transmission over almost all existing equipment interfaces of “old switching systems, while preserving all types of existing signaling that occurred during circuit switching.

,

Consider the operation of the unified module 19, shown in figure 2.

We begin to consider the operation of the unified module 19 from the moment when the subscriber picks up the telephone set 9 (see Fig. 1), closes the loop of the subscriber line (not shown in Fig. 2) and occupies that subscriber set 4 (see Fig. 1) to which this subscriber line is connected. Group 2 subscriber sets in conjunction with the group switching subscriber device 5 of the switching system forms a channel switch. In outgoing communication, the channel switch is implemented as a subscriber unit 38 for outgoing communication, which with its output 77 is connected to one of the inputs 76 of the matching device (SU) 36 of the outgoing communication of the second group of matching devices. In matching device 36, analog to digital signals are converted. The output 66 of the connecting device 36 is connected to the SG signaling gateway 26 by a bi-directional bus - a signaling channel through which, when an outgoing connection is established, signaling information is transmitted between the matching device 36 and the SG signaling gateway 26.

The output 68 of the matching device 36 is connected to the media gateway 28 MG bi-directional bus - information channel (this channel is connected to the input 55 of the media gateway 28 MO).

The input 71 of the matching device 36 is connected by a control channel to the output 70 of the asynchronous multiplexer - demultiplexer 30.

On these links (synchronization channel, information channel and control channel), an outgoing communication matching device 36 interacts with the basic elements of a unified packet information transmission module 19.

Signal SH.LUYZ 26 SG with SIP protocol and MG media gateway provide the formation of information packets intended for transmission over a data network. Suppose that the connection should go in the direction of the in-house communication, which includes the matching device 37 incoming communication of the third group of matching devices.

So, in the unified module 19 is the formation of packets of information that (packets) relate, in particular, to the connection, the source of which is the telephone installation 9 in question (see Fig. 1).

The SG signaling gateway 26 communicates with the MG media gateway 28 over the control bus 33. As a result, when organizing the connection from the telephone installation 9 during the transmission of each packet of information, the selection of the same connection route with the accuracy of a particular matching device 37 is made.

Installed via the incoming connection matching device (SU) 37 of the third group of matching devices, the in-house connection from the output 74 of the matching device 37 goes to the input 75 of the incoming communication unit 39 and then through the user line 10 to the subscriber telephone device 8 (elements 8 and 10 are shown in Fig. 1).

It should be noted that the input 73 of the matching device 37 is identical (in its functions) to the input 71 of the matching device 36, the input67 is identical, respectively, to the input 66, and the input 69 is identical, respectively, to the input 68. Identity of the specified inputs of the matching devices 36 and 37 implies the identity their interaction with the main elements of the unified module 19 packet information transfer (this interaction is disclosed when considering the operation of the matching device 36 outgoing communication).

Suppose that the subscriber of the telephone installation 9 establishes communication in the other direction in which the transmission system 61 is installed. Assume also that the transmission system 61 is so physically outdated that it is impossible to organize high-quality data transmission for voice transmission. In this clause 11, it is necessary to use the transmission system 61 in the form in which it was used before upgrading the communication network using the proposed technical solution (i.e., the transmission system 61 should be used in channel switching mode).

Here it is necessary to dwell on the features of the claimed technical solution, which first for all (100%) connections makes the transition from channel switching (which takes place at the level of subscriber unit 1 (see Fig. 1) to packet switching, and then, only for those directions communications in which the transmission of packets while maintaining the required quality of communication cannot be ensured, performs the reverse transition from switching packets again to switching channels (more precisely, to the formation of restored channels).

In this case, the actual “switching is carried out by the technical means of the signal gateway 26 SG and the media gateway 28 MG (it is with their help that the system 61 is selected).

Note: to organize the joint work of elements 31, 32, 36, and 37 with gateways 26 and 28, ACI1 {chronic multiplexordemultiplexer 30 is used. The construction of the multiplexordemultiplexer is traditional, and this construction and the principle of its operation are known from numerous sources of information. In this regard, in the present description, the operation m) of the transmitter-demultiplexer is not detailed.

When forming the restored channels, it is necessary to additionally track not only the transmission direction (transmission route), but also the channel number on which the connection was first established (i.e., it is necessary to select the connection route in more detail). This feature is provided by the SIP protocol. When organizing a connection.

uses bus 46, through which signal information of the required type (1ВСК, 2ВСК, inductive code, Mink code, signals of internal interfaces of equipment of various types of switching systems, systems, etc., is transmitted to a matching device (SU) 31, 32, 36, and 37) )

Note: it should be noted that with modern production technologies and a modern element base, multiple information conversions, namely, the formation of connection information from an analog form to digital, the subsequent conversion of this connection information into information packets, the next conversion of information packets in matching devices 31, 32, 36 and 37 and the restoration of analog B1ada of this information (in equipment installed on the same switching system) do not practically lead to loss of quality Communication Properties.

Thus, in the framework of the same switching system, for all (100%) connections, a transition from channel switching to switching information packets is provided, and only a part of these connections provides a transition from digital packets of connection information to the original analog form of this information (i.e. e. the formation of restored channels).

Consider the operation of the switching system shown in FIG. 3.

The unified module 19 for packet information transmission with three groups of matching devices (matching devices 31, 32 transmission systems, matching devices 36 for outgoing communication and matching devices 37 for incoming communication) is connected to a group switching subscriber device 5 of the electromechanical switching system through outgoing cord kits

78 and through the incoming cord sets 79.

When describing the operation of the inventive switching system of FIG. I the possibility of the indicated inclusion of cord sets 78 and 79 was agreed.

Connecting the matching devices 36 and 37 to the group switching subscriber device 5 of the electromechanical switching system is not directly, but through the cord sets 78 and

79 allows you to significantly simplify the matching devices 36 and 37 and significantly reduce their cost, because the fulfillment of part of the functions for the implementation of signaling tasks (transmission of signals of interaction between electromechanical automatic telephone exchanges) can be retained for cord sets 78 and 79. In all other respects, the operation of the switching system of FIG. 3 is identical to the above operation of the switching system of FIG. 1.

Consider the operation of the switching system of FIG. 4.

In FIG. 4 shows a Proxy Server forwarding module 80 connected to a LAN switch 29 - Ethernet switch. This module 80 provides the switching system with transit functions, i.e. call forwarding functions when a connection (in packet information transfer) coming, for example, from a transmission system 62 (from one switching system of a communication network) to a unified module 19, more precisely, to a modulator-demodulator 32, can be processed using module 80 so that it will be transmitted through the modulator-demodulator 31 to the transmission system 61 (to another switching system of the communication network.

Note: 1) consideration of the functioning of 80 forwarding itself, as well as consideration of the functioning of the software of the entire communication system as a whole beyond the scope of this application and it is considered 2) above, speaking about elements 31 and 32, we talked about matching devices of the first group of matching devices, now (without contradicting ourselves) we are talking about modulators and demodulators. The thing is that ecmi transmission systems 61 and 62, by their technical characteristics, are able to transmit data at a speed that ensures the required quality of communication, then they use modulator-demodulators as elements 31 and 32, and if transmission systems 61 and 62 do not provide data transmission with the required communication quality, then matching elements of the first group of matching devices are used as elements 31 and 32.

In FIG. 5 depicts intelligent subscriber terminals 82 and 83, which are connected to the SG signal gateway 26 and to the MG media gateway 28 via a LAN switch 29 - Ethernet switch. The digital information of smart terminals 82 and 83 is processed by gateways 26 and 28 in the same way as described above.

Consider the operation of FIG. 6 and 7 unified modules in accordance with the claimed technical solution.

In these figures, the access paths to the Internet network 91 and to the PSTN network 92 are shown (in the first case, through the router 87, see Fig. 6, in the second case, through the gateway 89, see Fig, 7).

Router 87 and gateway 89 are connected via buses 88 and 90, respectively, to the LAN switch 29 - Ethernet switch. This connection allows the gateways 26 and 28 (SG and MO, respectively) to forward information packets either to the Internet (the path is shown above) or to the PSTN network (the path is also shown above).

Thus, access to the Internet network 91 and / or to the PSTN network 92 can be made from any subscriber telephone installation 8, 9 (see FIG. 1) or a subscriber smart terminal 82, 83.

Let us dwell on the presence in this proposal of an overwhelming positive effect, which consists in the fact that without any changes and additions to the hardware of the claimed switching system, it is possible to solve one of the urgent tasks for telecom operators in Russia - protection against unauthorized access to unauthorized access use of communication. This problem is solved by identifying additional features of the above technology packet transmission based on the SIP protocol (or its modifications).

It was indicated above that the SIP protocol can provide the ability to interact with the equipment of the upgraded “old switching systems on almost all internal interfaces of the equipment of these systems. We see an overwhelming positive effect in the fact that any of these internal interfaces can be additionally repeatedly modified by means of the SIP protocol, moreover, this modification can be performed in real time by the commands of subscribers of standard (standard) subscriber telephone installations (telephones and impulse or tone dialing).

And this opportunity, in turn, allows you to provide all (100%) subscribers of the claimed switching system with additional services that provide protection against unauthorized access:

- communication by password (while maintaining access to special services without entering a password),

-restriction of various types of outgoing calls at the initiative of the subscriber (such as long-distance calls, international calls, mobile communications through the index of access to the direction of long-distance calls, paid reference and information services, as well as local calls) while saving to special services, regardless of the types entered by the subscriber communication restrictions

-the ability to independently order (cancel) NSD services by the subscriber himself, without operator’s participation,

- restriction of various types of outgoing communications (see above) at the initiative of a telecom operator in case of non-payment by a subscriber of bills for telecommunication services issued to him,

-restriction of incoming communication at the initiative of the telecom operator in case of non-payment by the subscriber of bills for telecommunication services issued to him

The interaction of the subscriber with the unified module 19 packet information should be carried out either using standard pulse decade signals of the dialer of the subscriber telephone installation, or using standard tones in the two-group tone code DTMF.

Due to the fact that the telephone load is compressed in the outgoing subscriber unit 38, the unified module 19 is entrusted with the task of determining the number of the calling subscriber (regardless of the task of protection against unauthorized access considered now) (this is done for the subsequent time-based recording of connections necessary for billing for the use of communication services). The crawling number of the caller can be used for the task of protection against unauthorized access. asking everyone to call this phone number of the War 36 of the second group of matching devices. The signaling processes (including determining the number of the subscriber) are controlled by the signaling gateway 26. After the calling subscriber is determined, the signaling gateway 26 selects the algorithm for interacting with the subscriber television device to the best of its ability. The following modifications are possible: if the subscriber does not use protection against unauthorized access, then the signaling gateway 26 provides the usual reception of the called subscriber's number (this was discussed above), if the subscriber ordered the protection from unauthorized access in the form of the service “password communication, then after receiving and analyzing the number the caller with a signaling gateway 26 under his control from the media gateway 28 the subscriber will be sent a voice message “enter password. After that, the signal gateway 26 will interpret the first digits of the number dialed by the subscriber as a password (i.e., the interaction algorithm will be modified by the signal gateway), if the subscriber ordered the PSD protection service as a restriction of long-distance and international calls, then the signal gateway 26 provides the usual reception of the first digits of the called subscriber’s number (and the first digit determines the exit towards long-distance and international calls), and (another modification of the interaction algorithm) will analyze this figure. If the subscriber as the first digit dialed the number "8 (exit towards intercity and international calls), then the subscriber will be sent from the media gateway 28 under the control of the signaling gateway voice message type" this type of communication is prohibited. If the subscriber dialed another number, then the signaling gateway 26 will switch to the usual reception of the number of the called subscriber (this was discussed above). if the subscriber needs to carry out an order (cancellation) of services for protection against unauthorized access, he dials a certain number (one unique for all subscribers of the telephone network), for example, number 555-55-55. In this case, the signal gateway 26 performs the usual reception of the number, and after the end of the analysis analyzes the entire number (in our example, seven-digit). When receiving numbers 555-55-55 under the control of the signal gateway 26 from the media gateway 28, a voice message is sent to the caller “dial the service code. The subscriber dials the service code (ordered or canceled), for example, the code "23, after receiving which, in the signal gateway 26 under his control, the subscriber receives from the media gateway 28 the voice message" the service is ordered. This is another modification of the interaction algorithm. , 3 // lfr Examples of the use by the subscriber of the NSD protection service could be continued, but a more detailed consideration of them is beyond the scope of this application.

For us, it is important that the signaling gateway 26 selects the modification of the interaction algorithm required for servicing the given subscriber when implementing the task of protecting against unauthorized access by the number of the calling subscriber.

{} -3 //

first group of matching devices

for coordination of the main nodes

equipment claimed switching

systems with three-wire physical

connecting lines of communication directions

to (from) other (other) switching

(switching) systems (systems)

Description, functional diagram, circuit diagram (on 3 sheets)

.

24

Appendix 2

to the application

"Switching system

Implementation example

Matching device 3-wire universal

CPSU is designed for interfacing with three-wire physical connecting lines (SL), custom-connecting lines (ZSL) and connecting long-distance lines (SLM). Interaction with the oncoming station is carried out by means of the signal code given in Table. 7.13 and 7.14 of the Guidance document on the national system of automated telephone communications (OGSTFS).

CPSU includes the following functional groups:

a node for interfacing with an in-line PCM line;

control device;

overvoltage protection circuit;

incoming matching devices (# 1 ... # 4);

outgoing matching devices (# 5 ,,. # 8); The composition of each coordinating incoming device includes:

registers of reception and transmission of control signals;

codec;

interface node of the colloquial tract;

transmitter; neck signals of wires a and

wire line transmitter

receiver of line signals of wires a and

wire line receiver

indication unit; The composition of each device matching outgoing includes:

registers of reception and transmission of control signals;

codec;

interface node of the colloquial tract;

wire line transmitter

wire line transmitter

wire line transmitter

wire line receiver

wire line receiver

wire line receiver

control signal transmitter;

indication unit;

The interface node with the in-house PCM line consists of gate and channel interval gate formers, a reception register of 16 KIs, switching buffers of transmitted SUVs, a 16xKI transmission register.

The control device provides the conversion of SUV into linear signals transmitted over a three-wire physical line. It consists of a single-chip microcontroller, a data bus buffer,

(RAM)

encoders addresses of the registers of reception and transmission of control signals of matching devices, registers SUV.

An overvoltage protection circuit is designed to protect surge matching devices from connecting line wires.

The codec provides analog-to-digital / digital-to-analog conversion of the spoken path.

The interface section of the colloquial tract contains an isolation capacitor, an isolation transformer, a differential system that decouples the colloquial path of reception and transmission, and elements of protection against high potentials on the wires a and b.

The display unit allows maintenance personnel to determine the current status of the trunk. Optical signaling is provided by a two-color indicator. When the trunk is busy, the indicator lights up in green, and when the line is blocked, it lights up in red.

In the device matching incoming:

The linear signal transmitter of the wires a and b is designed to generate linear signals transmitted to the opposite set by positive and negative potentials through the wires a and b of a three-wire physical line. It consists of two current sources and four switches. The first current source is involved in the formation of signals transmitted by the negative potential, and the second - in the formation of signals transmitted by the positive potential. Negative potential on wire a and positive potential on wire b are always fed simultaneously because the corresponding switches have a common control circuit.

The wire linear signal transmitter c is designed to generate linear signals transmitted to the oncoming set with negative potential via a wire from a three-wire physical line. It is a controllable current source. The magnitude of the current transmitted to wire c is determined by the control signals at the outputs of the control unit. When interacting with the oncoming automatic telephone exchange of the decade-step system, a jumper is installed in the transmitter in the group of jumpers ХТ2.

The receiver of the linear signals of wires a and b consists of two sensors that convert the linear and control signals transmitted from the oncoming set of positive and negative potentials along the wires a and b into the signals of logical 1 and logical O and transmits them to the control device. A sensor connected to the first current source of the linear signal transmitter of the wires a and b converts the positive potential on the line wire to a logical O signal. A sensor connected to the second current source of the transmitter of the linear signal wires a and b converts the negative potential on the line wire to the logical signal ABOUT.

.5

by wire with, into the logical O signals and transmits them to the control device. When working with a PBX system, you must install a jumper in the KhTZ jumper group, otherwise a jumper in the same group. In the device matching outgoing:

The linear signal transmitter of wire a is intended for the formation of linear signals transmitted to the oncoming set with negative potential through the wire of a three-wire physical line. It is a key that connects the wire a to the station battery through a resistor, supplementing the choke resistance to the required value of 1 kOhm. This key is turned on by a logical O signal transmitted by the control device.

The linear signal transmitter of wire b is designed to generate linear signals transmitted to the oncoming set with positive potential via wire b of a three-wire physical line. A signal is used to transmit signals through the trunk and back-ground lines, which connects the wire b to the + station battery through a resistor, supplementing the choke resistance to the required value of 1 kOhm. The inclusion of this item 11 occurs when a logical O signal is transmitted from the control device. The switch transfers the CALL and RESET signals via the SLM (the remaining signals are also transmitted via the SLM via the key). The switch turns on when a logical 1 is supplied from the control device to the RS input of the trigger. The threshold device in the event of a switch overload on the current turns off the RS-trigger.

The wire linear signal transmitter c is designed to generate linear signals transmitted to the oncoming set with positive potential via a wire from a three-wire physical line. It consists of a switch, a threshold device operating similarly to a switch and a threshold device of a wire transmitter b.

The receiver of the linear signals of the wire a converts the linear signals transmitted from the counter set by the positive potential along the wire a to the logical O signals and transmits them to the control device.

The receiver of the linear signals of the wire b converts the linear signals transmitted from the counter set by the negative potential along the wire b into the signals of the logical O and transmits them to the control device.

The receiver of the linear signals of the wire s converts the linear signal LOCK, transmitted from the counter set by removing the negative potential from the wire s, into a logical signal 1 and transmits it to the control device.

The control signal transmitter is designed to generate battery pulses when transmitting numbers to the oncoming set with a ten-day code. It contains two keys that provide connection to the wires a and b of the line + and - of the station battery, respectively. In order to avoid distortion of pulses by elements of the interface node, acceleration e :: // x 5T

the correct path, the latter is turned off during dialing using a relay.

Marking. On the front of the TEZa printed circuit board, the decimal number of the TEZA is 3.080.892, its abbreviated name is SUZU, the position designations of the elements, and the serial number are marked on the front side. The decimal number of the printed circuit board is printed on the mounting side.

JU - 3 // tf7

Claims (6)

1. A switching system comprising a subscriber unit with a group of subscriber sets and a group switching subscriber device, inputs of subscriber sets of a group of subscriber sets on subscriber lines are connected to subscriber telephone installations, and their outputs are connected to the first inputs of the group switching subscriber device, with the first outputs of the group subscriber switching device connected to the first inputs of the group part of the switching system, the first group of outputs of the group part This switching system is connected to transmission systems in the direction of other switching systems, and the second group of outputs of the group part of the switching system is connected to the second inputs of the group switching subscriber device, the second outputs of which are connected to the said group of subscriber sets, while the group part of the switching system has second inputs related to transmission systems in directions from other switching systems, characterized in that the group part of the switching system is it is in the form of a unified module of a packet information system containing hardware and software tools, which include a signaling gateway (SG) with the Session Initialization Protocol (SIP) or a modification of this protocol, a media gateway (MG), a local switch computer network (LAN) - Ethernet switch, asynchronous multiplexer-demultiplexer and modulators-demodulators and / or the first group of matching devices for transmission systems, as well as the second group of matching devices for outgoing communication and the third group according to incoming communication devices, moreover, the signaling gateway SG and the media gateway MG are interconnected by a bi-directional control bus, the LAN switch is connected to the signaling gateway SG, the media gateway MG and the inputs of connecting subscriber terminals, the output of the signaling gateway SG is connected via a bi-directional PCI bus with the input of the asynchronous demultiplexer multiplexer, and on the bi-directional signaling bus with the first inputs / outputs of modulators-demodulators and / or the first group of matching devices of transmission systems, the second group of matching devices three outgoing communications and a third group of matching incoming communication devices, the second inputs / outputs of which are connected to the outputs of the asynchronous multiplexer-demultiplexer, and the third inputs / outputs of which are connected to the information output / input of the MG media gateway, while the outputs / inputs of modulators are demodulators and / or the first group of matching devices of the transmission systems are connected to the inputs of the transmission systems, the inputs / outputs of the second group of matching devices of the outgoing communication are connected with the aforementioned first output of the group subscriber communication Discount device outputs / inputs of a third group of terminating devices incoming communication associated with said second input of the switching device of the subscriber group. 2. The switching system according to claim 1, characterized in that said inputs / outputs of the second group of matching outgoing communication devices are connected to said first outputs of a group subscriber switching device via electromechanical cord outgoing sets or equipment of electromechanical switching systems similar to cord sets, and said outputs the inputs of the third group of matching devices for incoming communications are connected with the aforementioned second inputs of the group subscriber switching device TVA through electromechanical cord input sets or equipment of electromechanical switching systems similar to cord sets. 3. The switching system according to claim 1 or 2, characterized in that a forwarding server (Proxy-Server) for incoming connections - communication sessions, whose bidirectional input / output is connected to the LAN switch - Ethernet switch, is introduced into the unified module. 4. The switching system according to claims 1 or 2 and 3, characterized in that smart terminals with SIP protocol, such as a SIP telephone terminal and / or computer SIP terminal, are connected to the LAN-Ethernet switch. 5. The switching system according to claims 1 or 2-4, characterized in that a router is introduced into the unified module, the first bi-directional input / output of which is connected to the LAN switch - Ethernet switch, and the second bi-directional output / input of which is connected to the Internet. 6. The switching system according to claims 1 or 2-5, characterized in that a gateway is introduced into the unified module, the first bi-directional input / output of which is connected to the LAN switch - Ethernet switch, and the second bi-directional output / input of which is connected to the public telephone network use - PSTN network.