FR2776876A1 - Secure telex transmission method - Google Patents

Abstract

The method involves the telex data exchanged between one of the terminals (1) and the central telex unit (5) being, on one part, transmitted along a replacement data transmission network (3), and on the other part, along a bridge passage (4) connecting the replacement network to the central telex. The adaptor and bridge passer allow the telecommunications network to emulate the previously used telex network.

Description

A Telex transmission method, telex terminal adapter,

  network terminal and gateway for implementing the method.

  For the transmission of written messages, of which a certain trace must be able to be kept, the telex network offers subscribers various services such as, for example, the guarantee of identity between the text received and the text sent. This network also provides certification of the identity of

  corresponding and provides the instants of the messages.

  These services thus offered are therefore essentially legal in nature.

  Technically, the telex network is now overtaken by modern data transmission networks, such as the INTERNET computer network, for example with regard to transmission speed. However, the latter do not offer the above "legal" services, so the telex network retains some

  activity, even if it declines.

  Therefore, it must be maintained, but it becomes relatively expensive because difficult to amortize with a declining number of subscribers.

  The present invention aims to solve this problem.

  To this end, the invention firstly relates to a method of transmitting telex data between two telex data processing terminals through a telex exchange, the telex data between at least one of the terminals and the telex exchange being, on the one hand, transmitted through a modernization data transmission network and, on the other hand,

  passage of the modernization network, adapted to the central telex.

  Thus, this amounts to grafting, on the telex exchange, a data transmission network other than the telex network, in order to extend the ramification thereof to the various subscribers, or simply to replace

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  sections of transmission lines of the telex network by lines of the

  modernization network, like the RTC.

  As the modernization network is only a purely physical extension of the telex network and the latter therefore retains its exchange providing telex services, these are retained for the whole

  subscribers, even those connected through the modernization network.

  We can therefore, in the extreme, keep only a "central telex core", managing the various telex services, connected by a bundle of lines to the PSTN network, or any equivalent network, and acting as a telex service server for telex terminals connected to the PSTN. The maintenance costs of the telex network are thus considerably reduced, by the disappearance of specific lines for telex, and, in addition, any subscriber to the PSTN can

  subscribe to telex, without additional line.

  The invention also relates to a telex data adaptation gateway between a telex exchange and a data transmission network for implementing the method of the invention, comprising: - means for connecting to a telex exchange, - means for connecting to a data transmission network, - memory means, - means for managing a telex protocol, arranged to, in cooperation with the memory means, exchange data with the telex exchange and with the network through their means of connection and for

  connect these with each other.

  The invention further relates to a telex terminal adapter for implementing the method of the invention, characterized in that it comprises: - means of connection to a telex data terminal, - means of connection to a data transmission network, - memory means, - means for managing a telex protocol, arranged to, in cooperation with the memory means, exchange data with the terminal and with the network through the connection means and to connect

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  these with each other through means of adaptation of

telex data.

  The invention finally relates to a terminal for implementing the method of the invention, comprising - memory means for storing identification data of the terminal, - means for managing a protocol for, in cooperation with the means memories, exchanging telex data with another terminal, and - means of connection to a data transmission network

  modernization controlled by management resources.

  The invention will be better understood using the following description of a

  preferred embodiment of the method of the invention, with reference to the accompanying drawing, in which: - Figure 1 is a block diagram of telex terminals connected through the PSTN network and the telex network, implementing the method of the invention, - Figure 2 is a block diagram of a telex / PSTN adapter for terminal, - Figure 3 is a block diagram of a telephone network / telex adaptation gateway for a telex exchange, and

  - Figure 4 illustrates the stages of transmission of a telex.

  Terminal 1, comprising a standard telex data entry, printing and exchange set, is connected to telex terminal 7 through a chain made up, in order from first to second, by a telex / PSTN 2 adapter, the network PSTN 3, a gateway 4 for connection to a telex switching center 5 connected to the international telex network 6, and in fact therefore belonging to it but shown separately for the purpose of clarity.

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  Elements 2, 3, 4 thus replace, for terminal 1, the purely telex link presented by terminal 7 with another central office.

inside the telex network 6.

  The adapter 2, shown in detail in FIG. 2, comprises a time base 20 connected to a central microprocessor unit 21, a saved random access memory 22, interface circuits 23 of telex line and

  PSTN interface circuits 24, all connected by an internal bus.

  As a variant, the adapter 2 can be integrated into the terminal 1. In addition, the latter can consist of a non-dedicated data transmission terminal, such as a PC or fax machine, comprising the telex software necessary for the telex service. In other words, it is a

  superset of terminal 1, then multiservice.

  Instead of the PSTN, serving as a network for modernizing the telex network, one can use the ISDN (Digital Network with Integration of Services), the INTERNET, an INTRANET network, the network of the protected brand.

  TRANSPAC or any other data transmission network.

  The gateway 4, shown diagrammatically in FIG. 3, performs the reverse adaptation to that of the adapter 2, during a transmission of a telex message. This can intervene in one direction or the other, and in full-duplex, the gateway 4 therefore has in total the same functionalities as the adapter 2, with however an increased size since it can be connected to a plurality telex terminals (1) by

PSTN junction lines 3.

  Specifically, the gateway 4 comprises an assembly 41 comprising processing cards, such as that referenced 410, with the conventional telephone interface equipment, ensuring the interface with the PSTN 3 and the associated telex exchange 5, by respective circuits 411 and 413, connected to each other through a bidirectional format converter circuit 412 carrying out the ASCII / 5-telegraph code conversion. A circuit 414, with microprocessor and associated program memory, manages the card 410 and controls the various circuits, and in particular

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  manages the telex data exchange protocol through the link interfaces 411 and 413, which it controls for mutual connection by the circuit 412, in cooperation with a memory 46 of program and data, belonging to the set 41. A local network 44, here of the protected brand ETHERNET, connects various operating PCs 45 of a set 43 of operation. A supervision PC 40 connects the network 44 to a bus 42 for linking with the cards 41. Each card in the set 41 therefore has a functional structure similar to that of the adapter 2 and the

  detailed description of the adapter 2 therefore also applies to the gateway 4.

  The transmission of telex between terminals 1 and 7 will now be explained. Given the fact that the traditional transmission of telexes is well known, we will not recall all the details, in order to reserve

  the explanation of the new elements.

  For a call originating from terminal 1, illustrated by the sequence of steps in FIG. 4, which is explained in detail below, the latter emits a call signal, received by the telex interface circuit 23, which responds by a call confirmation signal. The subscriber using the terminal 1 then dials and transmits the telex number of the called terminal 7. The microprocessor 21, receiving this called number, controls the storage (22) and controls its transmission to the gateway 4 by the circuit 24 (comprising a modem or a switching circuit of the current of

loop of the PSTN line).

  The gateway 4 then calls the terminal 7 by taking an incoming trunk line from the telex center 5 and injecting the corresponding numbering. Terminal 1 can then send a telex to terminal 7, that is to say have it printed in real time, immediately,

  each character entered on terminal 1.

  For a transmission of a telex in the opposite direction, the terminal 7 calling the terminal 1, its call ends at the central office 5 for logical connection of the terminal 1 and is retransmitted to the gateway 4, which converts the telex number

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  called in a telephone number, according to a table in memory 46, and makes a corresponding call on the PSTN 3. After a process of identification of the terminal called 1 by the central telex 5 through the

  gateway 4, the two terminals 1 and 7 can communicate.

  The modem (24) mentioned above ensures the exchange of data and manages

the data flow.

  The program and data memory 22 includes an identifier of the subscriber or terminal 1, an identifier of the subscriber, choices of operating options by the subscriber and, in common, a bidirectional transcoding table for one to the other of an ASCII code, with 8 code moments, and a telegraphic character code having here 5 moments. Gateway 4 phone number and update date

  of the adapter 2 operating software are also stored in memory 22.

  The telex interface 23, connected to the terminal 1 directly or through a telex network, for example private, can be of the dual current voice or telegraph frequency type. As indicated, it detects and transmits on line various standardized signaling signals (fixed polarity of programmable duration) as well as character signals at 5 times, telegraphic, arrhythmic transmission, transmitted at the speed of 50 Baud (Bd). Provision may be made for other telegraph codes having more

of 5 moments.

  The microprocessor 21, with the memory 22, which communicates with the terminal 1 and with the network 3 through the respective interfaces 23 and 24 and puts these in connection with one another, ensures the conversion in one direction and in the other, between the 5-moment telegraph characters and the ASCII characters in the form of a byte of bits (see CCITT Notice S 18) and manages the detected errors: LED, error message to terminal 1

or the gateway 4.

  The PSTN 24 interface operates in full-duplex, here 300 Bd, to exchange in synchronous transmission, by its modem, ASCII characters (8 moments) between the processor 21 and the PSTN 3. The rest of the circuits

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  telephone interface 24 is conventional and ensures the catch and release of the PSTN line and the transmission and reception of the

  telephone numbering and signals.

  The memory 22 can also be downloaded from the supervision PC of the gateway 4 to update its software programs

telex operating.

  In the case of the variant, mentioned above, of a multiservice integrated terminal, it may be a fax machine with motherboard for PC, screen, printer, telex / PSTN adapter card (replacing adapter 2), 33 600 bit / s modem, telex software and, in this example, fax. The

  microprocessor 21 can operate in telex / fax time sharing.

  If a high speed modem is used in the adapter 2 or the variant terminal, this modem transmits by amplitude and phase modulation making it possible to simultaneously code, for example 4 bits by transmitting a particular state among 16. The bit speed is thus 4 times higher than the Baud speed, linked to the duration of each state. It is therefore no longer an asynchronous telegraphic transmission, so that the presentation of the bits to be transmitted must be adapted to group them by 4. In order to ensure the printing in real time of a telex message , the integrated terminal declares itself free to an incoming call only when its printer is available and in particular not used locally. To this end, it includes a circuit for determining the availability of the facsimile printer, in practice a central unit microprocessor managing the various facsimile circuits, a circuit which, through telex protocol management circuits controlling circuits for link to the adapter card, rejects an incoming telex call, if the printer is unavailable. In transmission, editing software helps in the creation of telex documents, which can be printed on command and sent in automatic and conversational mode to possibly several recipients chosen by

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  example in a terminal directory. The reception obeys the same

  principles, with automatic printing and identification of the gateway 4.

  The identification specifically described here relates to the equipment on either side of the PSTN 3, that is to say the terminal 1 and the gateway 4, the rest of the journey to the terminal 7 being conventional. For example, it involves the telephone number of the caller, or address in the network, received from the PSTN network (CLASS service for example), for control, or the name of the subscriber and a password. this must

grab.

  If the PSTN 3 network is replaced by an INTRANET type network or

  INTERNET, there is control of IP addresses.

  At the telex procedure level, identification takes place by exchange

telex codes.

  In the gateway 4, the memory 46 contains a table of subscribers, with the telex number of terminals like 1, their telephone call number and their callsign. The memory 46 is accessible from all the cards 410 by the bus 42. The terminals calling the gateway 4 are thus identified and authenticated by searching for the identifier, which they supply to the gateway 4, in the subscriber table. The supervision PC 40 collects the

  activity reports of maps 41, to draw up a logbook.

  The operating assembly 43 updates the data of the

  gateway 4 and collects state information from it.

  Figure 4 is a diagram explaining in more detail the exchanges of

  data when transmitting a telex from terminal 1.

  In a step 51, the terminal 1 sends online a call signal to which the interface 23 responds (52) with a call confirmation signal. The terminal 1 then sends (53) the requested number (terminal 7) and the microprocessor 21 then makes (54) a call on the PSTN 3 (line seizure). This responds (55) with a call confirmation signal

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  (dialing invitation tone) triggering the sending (56) of the number below

  above by the microprocessor 21. The PSTN 3 interprets this number to call (57) the gateway 4 which responds (58) by looping the PSTN line, which causes (59) the connection (2, 4) through the PSTN 3. The PSTN 3 is then transparent and connects the adapter 2 to the gateway 4 without

  interpret the signals exchanged, linked to the telex application.

  Thus, from step 51 to step 59, layers 1 to 3 of the OSI (Open Systems Interconnection) classification are processed, that is to say physical layer 1 specifying the analog aspect of the interfaces, and the layers 2 and 3 of logical adaptation of the signals exchanged (bit rate, etc.) and of the protocol for establishing and breaking a physical link

  (possibly temporal) through the PSTN network 3.

  The following steps 60 to 69 use the physical link thus established to process the OSI layers 4 to 7, that is to say the exchanges for a logical link, through the physical link, making it possible to carry out a determined application, here the telex, and in particular presenting

  receiver the data to be printed in a prescribed format.

  In step 60, the gateway 4 sends (41), to the adapter 2, an identification request, to which the latter responds (61) by sending back the subscriber code, identifying the subscriber this. In step 62, the gateway 4 transmits, to the central office 5, a call signal and, to the adapter 2, an authorized connection signal or, possibly, a rejected call signal, which goes

  stop the attempt to establish a telex connection.

  In step 63, the telex exchange 5 sends a call confirmation signal back, while in turn, in step 64, the adapter 2 sends back to the gateway 4 the requested telex number , which is retransmitted (65) to the exchange after step 63. The latter responds with a subscriber identity request signal at step 66 and, at step 67, the gateway 4 sends to the exchange 5 l identifier of the subscriber and establishes the connection between the central office 5

and adapter 2.

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  At this stage, the adapter 2 and the gateway 4 become transparent, in the sense that they are no longer interlocutors interpreting signals, but that they only transmit them, with formatting. It is the terminal 1 and the exchange 5 which then interact, at a step 68 during which the exchange 5 transmits sequences of conventional telex connections for, for example, time stamping and codes. In the next step 69, the central office 5 has become transparent and the

terminals 1 and 7 are connected.

  For a telex connection in the other direction, from terminal 7 to terminal 1, the above principles remain valid, that is to say that, as shown in FIG. 4, connection sections are gradually established from the calling terminal, by each time exchanging telephone and / or telex signals between the two entities at each end of the new section which must be established, this up to the addressee. The entity called above is the master of the dialogue with the other entity which calls it and which must therefore respond to requests for information made by the entity called, so that the latter accepts

  the establishment of the link section.

  An alternative embodiment will now be described.

  In the variant, mentioned above, in which the PSTN network 3 is replaced or supplemented by the INTERNET network or one or more INTRANET networks, the gateway 4 can be considered as a service provider server of the INTERNET 4, providing the telex services to terminals connected to the INTERNET and enabling them to establish, between themselves and with subscribers of the telex 6 network, data communications having all the attributes of legal certainty provided by a telex service, whether it is provided by the international telex network or simply by a PABX integrating the functionalities of the gateway 4 and the central telex 5. As mentioned at the beginning, the purely telex network 6 could thus eventually disappear as

  network, only the server 4 remaining, offering all the telex functions.

  The gateway function would be limited to the essentially software adaptation between the telex "world", that is to say the associated services and protocols, and there the external "world", such as the INTERNET 3, while the gateway functions of physical link with the telex 6 network would have disappeared with the latter. A connection of the INTERNET 3 with another data transmission network by the gateway-server 4 cannot however be excluded. Terminal 1, for example a PC, then includes Internet navigation software, or at least means for receiving it.

by download.

  The software for the telex function, and in particular the signaling exchange protocol, for example to verify the identity of the correspondent,

  can be downloaded to terminal 1 by calling server 4.

  The user of terminal 1 is here subscribed to the telex service, that is to say that

  the identity of terminal 1 is stored in server 4.

  To transmit a telex to another terminal, or to several, also connected to the INTERNET 3, the user of the terminal 1 calls the server 4, via the INTERNET 3, with identification of the terminal 1, according to the principle explained more high for the PSTN, and the server 4 notifies the call, by INTERNET 3, to the other terminal which connects to the server 4 and thus establishes a connection between the two terminals, after verification of the identity of the called. The verification of identity, of the terminal and of the subscriber using it, by the server 4 may include the verification of the INTERNET IP address and of a pair: name and password. Access control to terminal 1 can be provided, for example by code word to be entered

and / or smart card.

  The server 4 remains in series on the link connecting the two terminals, that is

  that is to say that this link crosses the telex "world" (414) and thus benefits from all the desired services (OSI levels higher 5 to 7, linked to the telex application), the INTERNET 3 simply offering physical support (level OSI 1) and lower OSI layers 2 to 4 for data transport. The circuits 414 manage in this case the INTERNET navigation and data transmission protocols for dialoguing with

  terminals calling or called by the server 4.

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  The subscriber can in particular carry out an automatic transmission of documents, in conversational mode and, likewise, can receive, by being alerted, documents originating from the server 4, associated with all the guarantees or attributes offered by the telex service, such as the identification of the caller, the called party, the date and time, the content of all or part

  message with protective encryption and a reference for archiving.

  This information is kept by the server 4.

  The dialogue protocol between the terminal 1 and the server 4, necessary for the telex service, may however, in its form, be different from that provided for on a conventional telex network, since it is sufficient that the information to be exchanged can be transmitted. The only condition is that the terminal 1 and the server 4 use the same protocol. If it is necessary to reach a terminal (7) connected to the telex network 6, then the server 4 performs the adaptation function

  the standard protocols and format provided for the telex network 6.

  The PC 1 can therefore be a general-purpose terminal, not specifically telex, with navigation software and communication software for establishing connections with any server or terminal whatsoever and in particular the server 4. It is only in the latter case that the signals and message data exchanged are adapted to the telex application. The PC 1 is thus particularized, compared to a conventional INTERNET terminal, only by the fact that it includes software

  telex application to communicate with server 4 (OSI layers 6 and 7).

  The adapter 2, intended for the connection of a terminal 1 specifically telex, adapter treating lower OSI layers, such as speed adaptation, is no longer necessary since it can be provided that the telex application software uses lower OSI layers, such as speed adaptation (level 2), directly compatible with INTERNET 3, in packet mode. In other words, it is the upper layers of the presentation software and telex application (levels 6 and 7) which replace the adapter 2 here for the adaptation between terminal 1 and the INTERNET 3, transparent to data. . However, there are link circuits to adapt the PC 1

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  INTERNET 3, but these are not application-specific

determined, like telex.

  The server 4 thus offers telex services to any general-purpose terminal, through a non-specific data transmission network. As indicated above, in the case where the server 4 links together two terminals connected to the INTERNET 3, therefore without crossing the telex network 6, it can be provided that the data (signals and messages) are processed in the server 4 under the form in which they were issued by terminal 1, that is to say without transformation into the standard telex presentation. The circuit 412 for adapting to the standard is then unused since the server 4 then replaces the standard telex exchange 5 to loop the incoming INTERNET link over an outgoing INTERNET link to a called terminal. More specifically, the circuits 412 and 413 can be transparent, to connect the server 4 to the central office 5, which is then controlled by the server 4, like a connection matrix, to loop back the incoming INTERNET link onto an outgoing link 411 to the terminal called. As in FIG. 4, the server 4 can exchange signals and data with the called terminal of the INTERNET 3, through the central 5. The central 5 can be integrated into the server 4 and be in the form of a local network, ETHERNET for example, to loop back any incoming INTERNET link 411 to any outgoing INTERNET link 411 at circuits 413, of ETHERNET interface. The server 4 offers all the telex services but then with data transmission formats and protocols adapted from origin to the transmission over the INTERNET 3. As for the INTERNET terminal described above, the server 4 is essentially of the INTERNET type and it also includes telex application software (upper levels of the OSI), avoiding the need for hardware or software

  additional for lower OSI layers.

  This avoids the need for a dedicated network and terminals

by telex.

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Claims (22)

  1.- Method for transmitting telex data between two terminals (1,7) for processing telex data through a telex exchange (5), the telex data between at least one of the terminals (1) and the telex exchange ( 5) being, on the one hand, transmitted through a modernization data transmission network (3) and, on the other hand, at the passage (4) of the network of   modernization (3), adapted to the central telex (5).   2.- The method of claim 1, wherein the data is adapted by converting from one to the other a telegraph code and a code ASCII.   3.- Method according to one of claims 1 and 2, wherein, during   the arrival of a call (57) in the telex exchange (5) coming from the terminal (1) connected through the modernization network (3), a communication is established between the terminal (1) and the telex exchange ( 5) by answering the call (58) by taking a line from the modernization network (3) and requesting (60), from the calling terminal (1), identification data for   before accepting the address (64) of the called terminal (7).   4.- Gateway (4) for adapting telex data between a telex exchange and a data transmission network for implementing the method of claim 1, comprising: - means (413) for connection to a telex exchange (5), - means (411) for connecting to a data transmission network, - memory means (46), - means (414) for managing a telex protocol, agencies for, in cooperation with the means memories (46), exchange data with the telex exchange (5) and with the network (3) through their connection means   (411, 413) and to connect these with each other.   5. Gateway according to claim 4, in which there is provided, between the respective connecting means (411, 413), means (412) for adapting data arranged to convert ASCII code words into code words telegraph and vice versa. 2776876   6.- Gateway according to one of claims 4 and 5, in which it is   provided means (40) for downloading operating software.   7.- Gateway according to one of claims 4 to 6, in which it is   provided means (40) for editing a logbook.   8. Gateway according to one of claims 4 to 7, in which it is   provided means (41) for processing an identifier supplied by a io calling terminal.   9. Gateway according to claim 8, wherein the processing means (41) are arranged to identify and authenticate a calling terminal.   10.- Gateway according to one of claims 4 to 9, in which the   means (411) for connection to the network (3) are arranged to establish INTERNET type links.   11. Gateway according to claim 10, arranged (414) to operate as a telex server connected to a network of the type of that of the INTERNET (3). 12.- Gateway according to claim 11, integrating a connection network to loop one on the other two links (411) with the   network of the INTERNET type (3).   13.- telex terminal adapter for implementing the method of claim 1, characterized in that it comprises: - means (23) for connection to a telex data terminal (1), - means ( 24) for connection to a data transmission network, - memory means (22), - means (21) for managing a telex protocol, arranged for, in cooperation with the memory means (22), exchanging data with the terminal (1) and with the network (3) through the connecting means (23, 24) and to connect the latter with each other through means (21) 16 2776876 adaptation of telex data.   14. An adapter according to claim 13, in which means are provided for converting ASCII code words into telegraph code words and vice versa.   15.- Adapter according to one of claims 13 and 14, wherein it is   provided memory means (22) arranged to receive, by   download, telex operating software.   16.- Adapter according to one of claims 13 to 15, in which it is   provided means (41) for processing an identifier supplied by a calling subscriber. 17.- Telex terminal for implementing the method of claim 1, comprising: - memory means (22) for storing identification data of the terminal, - means (21) for managing a protocol for, in cooperation with the memory means (22), exchanging telex data with another terminal, and - means (24) for connecting to a data transmission network of   modernization (3) controlled by the management means (21).   18.- Terminal according to claim 17, comprising a standard telex assembly, in which there are adaptation means (21) for adapting, as a function of the modernization network (3), the telex data   exchanged with the latter through the connecting means (24).   19.- Terminal according to claim 18, also comprising means   (21) for processing data other than telex data.   20.- Terminal according to claim 19, comprising a fax machine.   21. Terminal according to claim 20, in which there is provided a circuit for determining the availability of the printer of the fax machine, 17 2776876   arranged to, through the management means (21), reject a telex call   incoming, if the printer is unavailable.   22.- Terminal according to one of claims 17 to 21, in which the   connecting means (24) are arranged to manage navigation software on a data transmission network of the type of INTERNET.