CH685083A5 - A method of facsimile communication. - Google Patents

Description

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CH 685 083 A5

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Description

Any fax machine can offer its operator, within the framework of the standardized T 30 protocol, exchanges between CCITT fax machines, to implement, with another fax machine of the same type, so-called private functions.

The T 30 protocol governs the transmission and reception of information and defines standardized frames, which any fax machine can exchange with any other, and non-standardized, or private, frames which can only be exchanged. between facsimile machines of the same type including and, a priori, of the same manufacturer.

Standardized screens

. DIS (Digital Identification Signal): this frame allows a called fax machine to announce its standardized capacities (characteristics of its modem, coding, speed, format, capacity to be read, etc.).

. DCS (Digital Command Signal): this frame allows a sending fax machine to announce, among the standardized capacities announced by a receiver, those it has chosen, in particular the transmission mode.

. DTC (Digital Transmit Command): this frame allows a calling fax machine, in the event of polling, to announce its standardized reception capacities and to issue a polling order.

Unstandardized frames

. NSF (Non Standard Facilities): this frame allows a called fax machine to announce its private capacities.

. NSS (Non Standard Command Signal): this frame allows a sending fax machine to announce among the private capacities announced by a receiver, those it has chosen, in particular the transmission mode.

. NSC (Non Standard Transmit Command): this frame allows a calling fax machine, in the event of polling, to announce its private reception capacities and to issue a polling order.

It goes without saying that any fax machine, which cannot manage private frames, must ignore them and continue its standard operation or interrupt transmission.

In the event of an incoming call, a fax machine called with private capacities picks up and therefore sends DIS and NSF, moreover without knowing whether the caller is a machine of the same type. If not, NSF will be ignored by the caller. If so, the caller transmits DCS and NSS and a TCF (Training check facilities) test frame. The called party sends a CFR (Confirmation to receive) acknowledgment frame, then the caller sends the message and an end of procedure EOP frame before the called party returns an MCF message acknowledgment frame. (confirmation message).

It is useful for the following to describe the sequence of a succession in private mode. A typical example is that of basic polling on a fax machine.

memory (data base polling). A central fax machine stores various documents in the database. Corresponding fax machines can call him and have any of these documents sent to him. The existence and updating of the databases of the central fax machine naturally depend only on its operator.

Basic polling is carried out as follows: a caller calls a called party to poll him. The called party issues NSF and DIS. The caller transmits NSC (document retrieval order) and DTC. The called party transmits NSS, DCS and TCF and the exchanges continue as before, the frames sent by the calling party and the called party being respectively reversed.

Finally, a facsimile protocol for the transmission of a message, in transmission or in basic polling of the message, between a calling fax machine and a called fax machine, one playing the role of sender and the other receiving the message , includes, before the transmission of the message, the announcement, by the called party, of its standardized and private capacities, the announcement, by the sender, of the choice of the capacities to be implemented and the sending, by him, of a test frame then the sending, by the receiver, of an acknowledgment frame.

Remember that when the called party announces its NSF private capacities, it does not know if the calling party is a machine from the same manufacturer. He also does not know if the caller will be able to support his NSF frame, in the event that its duration is excessive, and if it will not disturb him to the point of preventing him from reacting normally. The T 30 protocol fixes a maximum NSF frame duration, corresponding in this case to more than 80 bytes. For this reason, NSF frames generally do not exceed 30 bytes. As a result, many facsimile machines have been produced which effectively do not support NSF frames of more than approximately 30 bytes. In the case of such a calling fax machine and of an NSF frame sent by a called party of greater duration, a problem arises that the applicant has sought to solve, this problem being all the more frequent as the current fax machines are more private capacity to advertise.

To this end, the present invention relates to a facsimile communication method for the transmission of a message, between a calling facsimile machine and a called facsimile machine, one playing the role of sender and the other receiving the message, comprising , before the message is transmitted, an announcement by the called party of its own standardized and private capacities in response to a call from the caller, an announcement by the sender of the choice of the capacities to be implemented and a sending by the transmitter of a test frame then a sending by the receiver of an acknowledgment frame, characterized in that only part of the private capacities of the called party are announced by him in response to the call of the caller, which should be enough for the latter to start the communication in private mode, the rest of the private capacities of the called party being announced to the caller only during a subsequent private step to overcome NSF duration constraints, here from the standard T 30 protocol.

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Advantageously, during transmission, the called party announces the rest of its private capacities during a private acknowledgment frame.

Preferably, the called party announces, in response to the call, so-called main capacities sufficient to initiate communication in private mode. It may be the capacity of the terminal in terms of private protocols, of private document encodings, the encoding of which is also carried out on a small number of bits. With regard to the other called party's capabilities, called secondary, this may be the name of the station, the identification of the station's databases and mailboxes. These secondary parameters are generally not necessary for the caller to make his decisions. In addition, they are coded on a relatively large number of bits, for example 16 bytes in NSF commonly for the name of the station.

In the case where, in transmission mode, the private capacities announced by the called party in response to the call from the calling party are not sufficient for the calling party to start the communication, the calling party sends an unstandardized repeat command, modeled on the CRP (command repeat) frame of the T 30 protocol, and here referred to as the NS CRP frame, so that the called party completes, or repeats by completing it, the NSF frame sent in response to the call.

In basic reading, such a problem does not arise due to the inversion in the transmission of the frames. The called party then being the sender of the message, the capacities announced in NSF are always sufficient for the caller to recognize in the called party a terminal with private capacities. The problem that could arise, on the contrary, is that of the appellant's announcement of all his private capacities. But since sending the NSC frame is one of the steps in private mode, it can last as long as necessary, which avoids any difficulty.

The invention will be better understood using the following description, with reference to the accompanying drawing, in which

- fig. 1 is a flow chart of the exchanges to which a called fax machine is subjected and

- fig. 2 is a flowchart of the exchanges to which a calling fax machine is subjected.

In accordance with the inventive facsimile communication method, with reference to FIG. 1, a called fax machine, after picking up 1, transmits a DIS frame and an NSF frame of its main capacities 2.

The caller answers in one of the following four ways.

- It only sends a DCS 3 frame and the communication then continues according to the T 30 protocol.

- It sends an NS CRP 4 command and the called party completes or repeats the DIS-NSF 5 frames and returns the communication to the state it was in at the end of step 2.

- It sends DCS-NSS-TCF 6 frames, the DIS-NSF 2 frames being sufficient to start communication in private mode. The called party then sends an NS CFR frame of its secondary capacities 7.

- It sends DTC-NSC frames of all its capacities 8, for private polling. The called party then sends DCS-NSS-CFR 9 frames.

With reference to fig. 2, after the call 10 from the caller, the latter receives one of the following three responses from the called party.

- It receives only a DIS 18 frame and the communication continues according to the T 30 protocol.

- It receives DIS-NSF frames from the main capabilities of the called party 11, which are sufficient to initiate the communication. Then the caller sends

- either DTC-NSC frames in private polling 12,

- either DCS-NSS-TCF frames in transmission 13. Then, the called party responds in one of the following ways:

- it sends an NS CFR frame of its secondary capacities 14;

- it sends a NS FTT frame (Non Standard Fai-lure To Train) 15;

- it sends a regular CFR 16 frame;

- it sends a regular FTT 17 frame.

- It receives DIS-NSF frames of the main capacities of the called party 19, insufficient to initiate communication in private mode. The caller then sends an NSCRP command 20 before returning the communication to the state it was in before this step 19.

Claims (4)

Claims 1. A facsimile communication method for the transmission of a message, between a calling fax machine and a called fax machine, one playing the role of sender and the other receiving the message, comprising, before the message is transmitted, an announcement by the called party of its own standard (DIS) and private capacities (NSF), in response to a call from the caller, an announcement by the transmitter of the choice of capacities to be implemented (DCS-NSS ) and a sending by the transmitter of a test frame (TCF) then a sending by the receiver of an acknowledgment frame, characterized in that only part of the private capacities of the called party (NSF ) is announced by him in response to the call from the caller, which should be enough for the latter to start the communication in private mode, the rest of the private capacities of the called party being announced to the caller only during a subsequent private stage (NS CFR) to overcome time constraints (NSF). 2. A facsimile communication method according to claim 1, in which, in transmission mode, the called party announces the rest of its private capacities during a private acknowledgment frame (NS CFR). 3. A facsimile communication method according to claim 1, in which the called party announces, in response to the call, so-called main capacities codable on a low number of bits (NSF). 4. Method of facsimile communication according to 5 10 15 20 25 30 35 40 45 50 55 60 65 3 5 CH 685 083 A5 one of claims 1 to 3, in which, in transmission mode, when the private capacities (NSF) announced by the called party in response to the call from the calling party are not sufficient for the calling party to initiate the communication, the caller sends an unstandardized repeat command (NS CRP). 5 10 15 20 25 30 35 40 45 50 55 60 65 4