A real-time relay transmission method, device and system for facsimile data

Abstract

The embodiment of the application provides a real-time relay transmission method, device and system of facsimile data, which are applied to a first client front-end device, the first client front-end device is in communication connection with a first facsimile machine, and the method comprises the following steps: after call connection of the first facsimile machine and a second facsimile machine, the first client front-end device receives facsimile data sent by the first facsimile machine; the first client front-end device converts the facsimile data into an image file; the first client front-end device decomposes the image file into a plurality of image units, obtains a plurality of data packets through Internet protocol encapsulation, and sends the plurality of data packets to the second facsimile machine in real time through an Internet session protocol link.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of relay transmission technology, and in particular to a real-time relay transmission method, apparatus and system for fax data. Background Technology

[0002] Faxing is a traditional service in the Public Switched Telephone Network (PSTN) environment. The International Telecommunication Union (ITU) has successively introduced two types of fax specifications adapted to IP networks: one is a specification for real-time fax scenarios, and the other is a specification for store-and-forward methods.

[0003] Specifications for real-time fax scenarios define the network as providing a transmission channel, requiring it to be used solely for end-to-end negotiation and communication data between fax machines. However, in real-world network environments, IP networks inherently suffer from latency, jitter, and packet loss, which can lead to lower fax success rates, especially in scenarios with poor network quality.

[0004] The specification for store-and-forward (eFAX) defines a technical framework where a client-side front-end device (CPE) communicates with a fax machine (FAX), stores the fax data as a TIFF (Tag Image File) file, and then sends it to the recipient via email or HTTP. Therefore, this specification is also known as the eFAX standard. The core logic is store-and-forward: the image information scanned by the fax machine is first converted into a TIFF file, and then the TIFF file is sent to the recipient via email or HTTP. It is not a true real-time fax service. Besides creating a different user experience compared to traditional faxing (for example, with traditional fax machines, users receive immediate feedback on success or failure, while store-and-forward often requires a longer wait to confirm whether the fax has actually been delivered), this method also presents other problems. Since faxes are often used to transmit documents with extremely high timeliness and validity requirements, such as doctor's prescriptions and legal correspondence, this store-and-forward model not only undermines the real-time nature of faxing but may also lead to disputes or confusion regarding the validity of the documents. Summary of the Invention

[0005] The technical problem to be solved by the embodiments of the present invention is to provide a real-time relay transmission method, apparatus and system for fax data, which can receive, convert and transmit fax data in real time, restore the real-time interactive characteristics of traditional fax, and solve the feedback delay problem of store-and-forward mode.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0007] A real-time relay transmission method for fax data, applied to a first client front-end device, the first client front-end device being communicatively connected to a first fax machine, the method comprising:

[0008] After the call between the first fax machine and the second fax machine is connected, the first client front-end device receives the fax data sent by the first fax machine.

[0009] The first client-side front-end device converts the fax data into an image file;

[0010] The first client-side device decomposes the image file into multiple image units, which are then encapsulated using the Internet Protocol to obtain multiple data packets;

[0011] The first client-side device sends the multiple data packets to the second fax machine in real time via an Internet Session Protocol link.

[0012] Optionally, the first client-side front-end device converts the fax data into an image file, including:

[0013] Discrete sampling is performed on the analog image signal of the fax data to obtain discrete electrical signal data;

[0014] The electrical signal data is quantized to obtain a digital signal stream;

[0015] The digital signal stream is decoded to obtain digital fax information;

[0016] The digital fax information is encapsulated into an image file.

[0017] Optionally, the first client-side device decomposes the image file into multiple image units, encapsulates them using the Internet Protocol (IP) to obtain multiple data packets, including:

[0018] The image file is decomposed into multiple image units, and a unique identifier is added to each image unit;

[0019] The image unit is encapsulated using Internet Protocol to obtain multiple data packets.

[0020] Optionally, the first client-side front-end device transmits the multiple data packets to the second fax machine in real time via an Internet Session Protocol link, including:

[0021] The first client front-end device sends the multiple data packets to the second fax machine in real time via the Internet Session Protocol link through the second client front-end device.

[0022] Optionally, the first client-side front-end device transmits the multiple data packets to the second fax machine in real time via an Internet Session Protocol link, including:

[0023] The first client front-end device sends the multiple data packets to the second fax machine in real time via the Internet Session Protocol link, through the session boundary controller and the local area network gateway, and via the switched telephone network.

[0024] Optionally, the first client-side front-end device transmits the multiple data packets to the second fax machine in real time via the Internet Session Protocol link, through the session boundary controller and the local area network gateway, via the switched telephone network, including:

[0025] The first client-side front-end device converts the multiple data packets into intermediate fax data via the Internet Session Protocol link and the session boundary controller.

[0026] The first client front-end device converts the intermediate fax data into switched telephone network (STN) signals via the session boundary controller and the local area network gateway, and then sends them to the second fax machine through the STN.

[0027] Optionally, the first client-side front-end device transmits the multiple data packets to the second fax machine in real time via the Internet Session Protocol link, through the session boundary controller and the local area network gateway, via the switched telephone network, including:

[0028] The first client front-end device converts the multiple data packets into intermediate fax data via the Internet Session Protocol link, through the session boundary controller and the unified cloud platform, and then into switched telephone network signals via the local area network gateway, and sends them to the second fax machine through the switched telephone network.

[0029] This invention also provides a real-time relay transmission device for fax data, applied to a first client front-end device, the first client front-end device being communicatively connected to a first fax machine, the device comprising:

[0030] The transceiver module is used to receive fax data sent by the first fax machine after the call between the first fax machine and the second fax machine is connected.

[0031] The processing module is used to convert the fax data into an image file; decompose the image file into multiple image units, encapsulate them using Internet Protocol, and obtain multiple data packets;

[0032] The transceiver module is also used to send the multiple data packets to the second fax machine in real time via an Internet Session Protocol link.

[0033] This invention also provides a real-time relay transmission system for fax data, comprising: a first client front-end device and at least one relay transmission device, wherein the first client front-end device is communicatively connected to a first fax machine;

[0034] After the call between the first fax machine and the second fax machine is connected, the first client front-end device receives the fax data sent by the first fax machine.

[0035] The first client-side front-end device converts the fax data into an image file;

[0036] The first client-side device decomposes the image file into multiple image units, which are then encapsulated using the Internet Protocol to obtain multiple data packets;

[0037] The first client front-end device sends the multiple data packets to the second fax machine in real time through the Internet Session Protocol link of at least one relay transmission device.

[0038] Optionally, the first client-side front-end device sends the multiple data packets to the second client-side front-end device in real time via an Internet Session Protocol link, and the second client-side front-end device then sends them to the second fax machine; or

[0039] The first client front-end device sends the multiple data packets to the session boundary controller in real time via the Internet Session Protocol link; the session boundary controller then sends the multiple data packets to the second fax machine via the local area network gateway through the switched telephone network.

[0040] The above-described solutions of the embodiments of the present invention have at least the following beneficial effects:

[0041] The above-described solution of this invention converts fax data into image files and then splits them into multiple data packets, which are then encapsulated and transmitted via Internet Protocol, thereby improving anti-interference capabilities. Compared with the shortcomings of the store-and-forward mode in destroying real-time performance, this invention restores the instant feedback experience of traditional fax by receiving, converting, and transmitting data page by page / line by line in real time, meeting the document transmission needs of doctors' prescriptions, legal documents, and other documents with high timeliness requirements.

[0042] This technology avoids the significant differences in user experience compared to traditional faxing, as well as the long waiting time for confirmation of delivery, allowing users to receive instant feedback on fax transmission results. It also avoids potential disputes over document validity that may arise from store-and-forward faxing, meeting the needs of scenarios involving the transmission of important documents via fax.

[0043] It supports two network models: end-to-end (CPE to CPE) and network with SBC participation. Users can choose the model according to the actual network environment, which broadens the application scenarios and eliminates the need to adjust the transmission method due to network architecture limitations, thus improving the practicality of the method. Attached Figure Description

[0044] Figure 1 This is a flowchart of a real-time relay transmission method for fax data according to an embodiment of the present invention.

[0045] Figure 2 This is a schematic diagram of the end-to-end network model of the real-time relay transmission method for fax data according to an embodiment of the present invention.

[0046] Figure 3 This is a schematic diagram of the transmission of a network model involving a session boundary controller in the real-time relay transmission method for fax data according to an embodiment of the present invention.

[0047] Figure 4 This is a schematic diagram of the transmission of a network model involving a session boundary controller and a unified cloud platform in the real-time relay transmission method for fax data according to an embodiment of the present invention.

[0048] Figure 5 This is a schematic diagram of a real-time relay transmission device for fax data according to an embodiment of the present invention. Detailed Implementation

[0049] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0050] like Figure 1 As shown, an embodiment of the present invention provides a real-time relay transmission method for fax data, applied to a first client front-end device, the first client front-end device being communicatively connected to a first fax machine, the method comprising:

[0051] Step 11: After the call between the first fax machine and the second fax machine is connected, the first client front-end device receives the fax data sent by the first fax machine; specifically, the first fax machine can scan and send fax data in real time, page by page or line by line.

[0052] Step 12: The first client front-end device converts the fax data into image files; specifically, the first client front-end device converts the fax data received page by page or line by line in real time into image files.

[0053] Step 13: The first client front-end device decomposes the image file into multiple image units, which are then encapsulated using the Internet Protocol to obtain multiple data packets;

[0054] Step 14: The first client front-end device sends the multiple data packets to the second fax machine in real time via the Internet Session Protocol link.

[0055] Specifically, the first client-side front-end device can establish a physical connection with the first fax machine through a subscriber line interface, and the first client-side front-end device can interact with the first fax machine using PSTN.

[0056] The first and second fax machines can connect calls and relay fax data in real time through an end-to-end network model or a network model with SBC (Session Border Controller) participation.

[0057] If it is an end-to-end network model (CPE to CPE): the connection of the call between the first fax machine and the second fax machine may include: the first fax machine performs a dialing operation through the subscriber line interface to initiate a call to the first client front-end device (CPE); the first client front-end device generates a SIP-Invite signaling message and sends it to the second client front-end device (CPE) through the IP network (Internet Session Protocol link); after receiving the signaling message, the second client front-end device returns a SIP-180 Ring signaling message to trigger the second fax machine to ring; when the second fax machine goes off-hook, the second client front-end device sends a SIP-200 OK signaling message; after receiving the signaling message, the first client front-end device confirms that the call has been established.

[0058] In a network model involving a Session Border Controller (SBC): After the first fax machine initiates a call, the first client front-end device sends a SIP-Invite signaling message to the Session Border Controller deployed in the cloud; the Session Border Controller interacts with the local area network gateway through the core network to convert the SIP signaling message into a Public Switched Telephone Network (PSTN) signal, triggering the second fax machine to ring; after the second fax machine goes off-hook, the PSTN network returns a SIP-2000k signaling message to the first client front-end device through the local area network gateway and the Session Border Controller, completing the call connection.

[0059] In this embodiment, fax data is converted into image files and then split into multiple data packets, which are then encapsulated and transmitted via Internet Protocol to improve anti-interference capabilities. Compared to the shortcomings of store-and-forward mode in disrupting real-time performance, this invention restores the instant feedback experience of traditional fax by receiving, converting, and transmitting data page by page / line by line in real time, thus meeting the document transmission needs of doctors' prescriptions, legal correspondence, and other documents with high timeliness requirements.

[0060] To avoid the significant differences in user experience compared to traditional faxing and the long wait for confirmation of delivery, this method allows users to receive instant feedback on fax transmission results. It also avoids potential disputes over document validity that may arise from store-and-forward, meeting the needs of scenarios involving the transmission of important documents via fax.

[0061] It supports two network models: end-to-end (CPE to CPE) and network with SBC participation. Users can choose the model according to the actual network environment, which broadens the application scenarios and eliminates the need to adjust the transmission method due to network architecture limitations, thus improving the practicality of the method.

[0062] In an optional embodiment of the present invention, in step 11, after the call between the first fax machine and the second fax machine is connected, the first client front-end device receives the fax data sent by the first fax machine.

[0063] Specifically, the fax data is an analog image signal generated by the first fax machine through real-time scanning of a paper document page by page or line by line. The analog image signal contains the brightness and darkness pixel information of the paper document.

[0064] The first client-side front-end device receives the analog image signal in real time, ensuring synchronization with the fax machine's sending rhythm and preventing data backlog.

[0065] In this embodiment, the first client front-end device receives analog image signals in real time, page by page / line by line, in sync with the sending rhythm of the first fax machine. This preserves the user's familiar real-time interactive experience and avoids the feedback delay problem of the store-and-forward method, meeting the needs of scenarios with high real-time requirements, such as doctor's prescriptions and legal documents.

[0066] The no-data-backlog design prevents transmission interruptions or loss due to data accumulation. Combined with the brightness and darkness pixel information contained in the analog image signal, it can completely restore the details of paper documents, ensure the accuracy of fax content, and reduce disputes over document validity.

[0067] The real-time reception and synchronization mechanism is adapted to the IP network environment, which can avoid the impact of IP network latency and jitter on fax transmission, while continuing the reliable interaction between PSTN and fax machine, taking into account both real-time performance and transmission stability, and improving the success rate of fax services under VoIP network.

[0068] In an optional embodiment of the present invention, in step 12, the first client front-end device converts the fax data into an image file, including:

[0069] Step 121: Discretely sample the analog image signal of the fax data to obtain discrete electrical signal data; specifically, discretely sample the analog image signal of the fax data according to a set sampling frequency, that is, collect the instantaneous amplitude of the analog image signal once at fixed time intervals, and convert the continuously changing analog waveform into discrete electrical signal data; during the sampling process, the first client front-end device filters high-frequency noise in the fax data through a low-pass filter.

[0070] Step 122: Quantize the electrical signal data to obtain a digital signal stream. Specifically, map the discrete electrical signal data (voltage values) to preset quantization levels, with each level corresponding to a fixed voltage range. Convert the quantization level corresponding to each electrical signal data into an 8-bit binary number to form a continuous binary sequence (digital signal stream). Add simple check bits (such as parity check) to the quantized digital signal stream to detect errors that may occur during the quantization process (such as misjudgment of voltage value levels), ensuring the accuracy of the digital signal stream and providing reliable input for subsequent decoding.

[0071] Step 123: Decode the digital signal stream to obtain digital fax information; specifically, identify the MH / MR / MMR encoding format used in the digital signal stream and decode it according to the corresponding rules: for example, under MH encoding, restore the code symbol representing n consecutive black / white pixels to the actual pixel length to obtain the pixel sequence of each row; integrate all rows of data to generate structured digital fax information containing the pixel matrix of each page, resolution, page size, and total number of pages;

[0072] Step 124: Encapsulate the digital fax information into an image file; specifically, TIFF format is preferred (for multi-page and lossless transmission): write the TIFF file header (byte order, version, IFD offset), create an IFD for each page (record width, height, 1-bit depth, T.4 compression method, etc.), write the compressed pixel data according to the IFD offset, and associate multiple pages through the IFD linked list; PNG (lightweight single page) or JPEG (if compatibility is required) can also be selected, and metadata and pixel data are encapsulated according to the corresponding format specifications to generate a standard image file.

[0073] Specifically, when the first client front-end device receives fax data page by page, it is converted into a multi-page image file; when the first client front-end device receives fax data line by line, it is converted into a single-page long image file.

[0074] In this embodiment, step 121 uses low-pass filtering to remove high-frequency noise and fixed-interval discrete sampling to reduce analog signal interference and distortion; step 122 uses quantization and parity checking to avoid misjudgment of voltage values, providing double protection for the reliability of the digital signal stream; step 123 accurately decodes according to MH / MR / MMR encoding rules to restore pixel sequences and structured information, reducing errors throughout the process from signal to digital information, and laying an accurate data foundation for subsequent transmission.

[0075] TIFF format is preferred for encapsulation, supporting multi-page, lossless transmission, which is suitable for faxing multi-page documents; PNG (lightweight single page) and JPEG (for compatibility requirements) are also available to adapt to different usage scenarios; and multi-page or single-page long image files are generated according to the receiving method to flexibly match the fax data receiving rhythm and improve technical applicability.

[0076] Converting analog fax data into standard digital image files is compatible with IP file transfer technologies such as TFTP / FTP / HTTP, avoiding the adverse effects of IP networks on analog signal transmission. At the same time, the structured digital fax information and standard image format facilitate subsequent parsing and conversion, ensuring smooth fax transmission and helping to improve the success rate of fax services under VoIP networks.

[0077] In an optional embodiment of the present invention, in step 13, the first client front-end device decomposes the image file into multiple image units, encapsulates them via Internet Protocol, and obtains multiple data packets, including:

[0078] Step 131: Decompose the image file into multiple image units and add a unique identifier to each image unit; specifically, decompose the multi-page image file page by page into image units, each unit containing a complete page of data, and add a unique identifier (type 0x01 page by page, total number of pages, current page number, data length); or decompose a single-page long image file into image units, each unit containing a single row of pixel data, and add an identifier (type 0x02 indicating streaming, total number of rows, current row number, CRC checksum), to ensure that the remote end can reassemble according to the identifier;

[0079] Step 132: Encapsulate the image unit using Internet protocols to obtain multiple data packets. Specifically, TFTP (Trivial File Transfer Protocol), FTP (File Transfer Protocol), or HTTP (Hypertext Transfer Protocol) can be used to encapsulate the image unit. If TFTP is used, add a TFTP data frame header (opcode 0x0003, block number associated with unit sequence number) to each image unit, and then encapsulate a UDP header (source / destination port) and an IP header (first client front-end device and remote IP, protocol = UDP) to obtain multiple data packets.

[0080] In this embodiment, image files are decomposed according to their type. Multi-page files are split page by page, and single-page long files are split line by line. Combined with a unique identifier (including type, sequence number, data length / CRC checksum), the unit attributes and positional relationships are clearly defined, ensuring that the remote end can accurately sort and reassemble according to the identifier, avoiding data chaos. The CRC checksum can also detect streaming unit transmission errors, further ensuring data integrity.

[0081] The split image units are smaller, which reduces the amount of data transmitted in a single transmission and reduces the risk of large file transmission failures due to IP network latency and jitter. At the same time, it supports encapsulation of mainstream IP protocols such as TFTP / FTP / HTTP. For example, TFTP adapts network transmission by using data frame headers and UDP / IP headers, improving compatibility with different IP network environments and facilitating smooth data transmission.

[0082] Unitized transmission enables partial data retransmission. If a unit fails to transmit, only that unit needs to be retransmitted, instead of retransmitting the entire file, reducing bandwidth consumption and transmission time. Furthermore, information such as data length and block number in the identifier facilitates real-time monitoring of transmission progress, providing a basis for subsequent troubleshooting and transmission optimization, and further ensuring the stability of fax transmission under VoIP networks.

[0083] like Figure 2 As shown, in an optional embodiment of the present invention, in step 14, the first client front-end device sends the plurality of data packets to the second fax machine in real time via an Internet Session Protocol link, including:

[0084] Step 141: The first client front-end device sends the multiple data packets to the second fax machine in real time via the Internet Session Protocol link through the second client front-end device.

[0085] In step 141, the first client-side front-end device transmits the multiple data packets to the second fax machine in real time via the Internet Session Protocol link through the second client-side front-end device, including:

[0086] Step 1411: After the first client front-end device completes the encapsulation of each image unit, it immediately sends it to the second client front-end device through the Internet Session Protocol link. The sending interval is synchronized with the scanning rhythm of the first fax machine to avoid delays caused by buffer backlog. Specifically, the first client front-end device adds a unique identifier to each sent data packet and starts a timeout retransmission mechanism: if no confirmation signal is received from the second client front-end device within a preset time, the data packet is retransmitted to ensure that no key image units are lost.

[0087] Step 1412: After receiving the data packet, the second client front-end device first verifies the integrity of the network layer (such as IP header checksum, TCP / UDP sequence number) and filters out corrupted data packets; then it parses the transport layer data, extracts the image unit and its unique identifier (type, sequence number, check code, etc. added in step 131), and verifies the integrity of the unit data through the CRC check code; if it is a page-by-page unit (type 0x01): the second client front-end device sorts the units according to the total number of pages and the current page number, splices the units on the same page into a complete single page of data, and after accumulating until the total number of pages reaches the target, it encapsulates it into a multi-page image file; if it is a streaming unit (type 0x02): it sorts the units according to the total number of rows and the current row number, splices the pixel data of a single row in sequence, and after accumulating until the total number of rows reaches the target, it encapsulates it into a single-page image file (such as a single-page TIFF); the reassembly process is completely reversed from the disassembly rules of the first client front-end device, ensuring that the image file is consistent with the original file generated in step 124;

[0088] Step 1413: The second client front-end device reads the metadata (resolution, page size, etc.) and pixel matrix of the reconstructed image file to restore the digital fax information of step 123 (which is consistent with the decoding result of the first client front-end device).

[0089] Step 1414: The second client-side front-end device converts the digital fax information into switched telephone network signals (analog fax signals).

[0090] For multi-page image files: convert the pixel matrix of each page into an analog signal (such as MH-coded modulation signal) according to the page-by-page rhythm, send it to the second fax machine through the subscriber line interface, wait for the confirmation signal from the second fax machine after sending one page, and then send the next page, matching the page-by-page scanning rhythm of the first fax machine;

[0091] For single-page long documents: each line of pixel data is converted into an analog signal and sent in real time at a line-by-line pace, synchronized with the line-by-line scanning pace of the first fax machine, to ensure that the printing pace of the second fax machine is consistent with the receiving pace (to avoid paper jams or content misalignment).

[0092] Step 1415: The second client-side front-end device feeds back its status to the first client-side front-end device at the following nodes, forming a closed loop:

[0093] After receiving each image unit, the unit sequence number and reception status (success / failure) are returned via SIPINFO signaling, which is then used by the first client front-end device to trigger retransmission.

[0094] After completing the page / full page reorganization, a page completion signal (such as SIPMESSAGE signaling) is returned. Based on this, the first client front-end device sends feedback on the sending progress to the first fax machine (such as returning a busy tone / acknowledgment tone through the user line interface).

[0095] After all transmissions are completed, the second client front-end device sends a SIPBYE signaling message, the first client front-end device responds with an acknowledgment, and both parties release the session link, completing the entire fax process.

[0096] In this embodiment, the first client front-end device sends images in real time according to the image unit encapsulation progress, and the sending interval matches the scanning rhythm of the first fax machine to avoid latency caused by cache backlog; the second client front-end device sends analog signals by page-by-page and line-by-line rhythm for multi-page / single-page long documents respectively, to ensure that the printing rhythm of the second fax machine is consistent with the receiving rhythm, avoid paper jams or content misalignment, perfectly fit the real-time interactive characteristics of traditional fax, solve the problem of the experience disconnect of the store-and-forward method, and adapt to scenarios with high real-time requirements such as doctor's prescriptions and legal letters.

[0097] The sending end uses a timeout retransmission mechanism (retransmitting if no acknowledgment is received) to avoid losing critical image units; the receiving end first verifies network layer integrity (IP header checksum, TCP / UDP sequence number) to filter corrupted packets, and then confirms the integrity of image unit data through CRC check, thus reducing transmission errors through dual verification. Simultaneously, the second client-side front-end device provides status feedback through signaling such as SIPINFO, SIPMESSAGE, and SIPBYE at nodes such as unit reception, page reassembly, and completion, forming a closed loop: the first client-side front-end device can accurately trigger retransmissions and synchronize progress with the first fax machine, ensuring that fax data is controllable from transmission to reception, reducing disputes over document validity.

[0098] The second client-side front-end device reverse-engineers the image file according to the disassembly rules of the first client-side front-end device, ensuring that the reconstructed file is consistent with the original file. Simultaneously, it converts digital information into PSTN analog signals to meet the signal reception requirements of traditional fax machines, achieving seamless connection between the IP network (between client-side front-end devices) and PSTN equipment (fax machines). Furthermore, it supports IP protocol encapsulation such as TFTP / FTP / HTTP, combined with session link management, to avoid the impact of IP network latency and jitter on transmission, balancing the flexibility of IP networks with compatibility with traditional fax equipment, and improving the success rate of fax services under VoIP networks.

[0099] The first client front-end device can provide real-time feedback on the sending progress (busy tone / confirmation tone) to the first fax machine based on the feedback from the second client front-end device, allowing users to intuitively grasp the fax status; the unitized transmission design ensures that retransmission is only for lost / damaged image units, without having to retransmit the entire file, reducing bandwidth consumption and transmission time, and still enabling efficient transmission in scenarios with limited IP network resources, balancing transmission efficiency and resource costs.

[0100] In an optional embodiment of the present invention, in step 14, the first client front-end device sends the plurality of data packets to the second fax machine in real time via an Internet Session Protocol link, including:

[0101] Step 142: The first client front-end device sends the multiple data packets to the second fax machine in real time through the Internet Session Protocol link, via the session boundary controller and the local area network gateway through the switched telephone network.

[0102] Specifically, the first client front-end device reuses the Internet Session Protocol link during call establishment (which has been confirmed to be connected via SIP-2000k), and sends each data packet generated (step 132) to the session boundary controller immediately via the IP network according to the principle of sending data packet unit by unit in real time. The sending rhythm is synchronized with the first fax machine's page / line scanning (the corresponding data packet is sent immediately after scanning a page / line) to avoid delay.

[0103] The first client front-end device adds a unique identifier to the data packet. If it does not receive a reception confirmation (such as SIPINFO signaling) from the session boundary controller within a set time, it retransmits the data packet to ensure that no image unit is lost.

[0104] In this embodiment, the Internet Session Protocol link that has been confirmed to be connected via SIP-2000k during call establishment is reused, eliminating the need to re-establish the link and reducing link establishment time and resource consumption. Following the principle of sending data packets unit by unit in real time, the data packets are sent immediately after generation, and the sending rhythm is synchronized with the scanning of the first fax machine, avoiding delays caused by cache backlog, meeting the real-time requirements of faxing, and restoring the real-time interactive experience of traditional faxing.

[0105] By adding a unique identifier to data packets and combining it with a timeout retransmission mechanism, if no confirmation of receipt is received from the session boundary controller within a preset time, the data packet is immediately retransmitted. This can effectively avoid the loss of image units caused by packet loss in the IP network, ensure that fax data is intact and not lost during transmission, and reduce disputes over the validity of documents.

[0106] By connecting the session boundary controller with the local area network gateway and the switched telephone network, communication between the first client front-end device and the second fax machine in the traditional PSTN network is realized. This adapts to the CPE-SBC-PSTN network model, breaks through the limitations of pure end-to-end transmission, expands the application scenarios of the technology, and, relying on the advantages of SBC deployment in the cloud / core network, further ensures the transmission quality of IP network and improves the success rate of fax services under VoIP network.

[0107] like Figure 3 As shown, in an optional embodiment of the present invention, in step 142, the first client front-end device transmits the plurality of data packets to the second fax machine in real time via the Internet Session Protocol link, through the session boundary controller and the local area network gateway, via the switched telephone network, including:

[0108] Step 1421: The first client front-end device transmits the multiple data packets via the Internet Session Protocol link, and the session boundary controller converts the multiple data packets into intermediate fax data. Specifically, after receiving the data packets, the session boundary controller first verifies the integrity of the IP / TCP / UDP layer (such as checksum and sequence number) and filters out corrupted packets. Then, it parses out the image unit and its unique identifier (type, sequence number, checksum). After confirming the integrity of the unit through CRC check, it reassembles it into an image file according to the identifier (page-by-page units are concatenated according to page sequence number, and streaming units are concatenated according to line sequence number, the same as the reassembly logic of the second client front-end device in step 141).

[0109] Because the local area network gateway supports the IP fax standard, the session boundary controller converts the reconstructed image file (such as TIFF) into intermediate fax data: it encapsulates the pixel matrix, resolution and other information of the image file into data frames (including control signaling and image data blocks) to ensure protocol compatibility with the local area network gateway.

[0110] Step 1422: The first client front-end device converts the intermediate fax data into switched telephone network (STN) signals via the session boundary controller and the local area network (LAN) gateway, and sends it to the second fax machine through the STN network. Specifically, the session boundary controller sends the intermediate data to the LAN gateway in real time via an IP link (deployed in the same core network IDC room as the LAN gateway), and simultaneously transmits the status (such as data transmission progress) through SIP signaling.

[0111] After receiving the intermediate data, the local area network gateway decodes it into a switched telephone network signal (analog fax signal) supported by the PSTN network, and then connects to the public switched telephone network (PSTN) through the E1 / T1 trunk link.

[0112] The switched telephone network signal is transmitted to the telephone line where the second fax machine is located via the PSTN network, triggering the second fax machine's receiving process. The second fax machine then prints the received fax content in real time (page by page / line by line, matching the sending rhythm).

[0113] In this embodiment, the session boundary controller first verifies the integrity of the IP / TCP / UDP layer to filter corrupted packets, then confirms the integrity of the image unit through CRC check, and subsequently reassembles the image file in an orderly manner according to the identifier, which is consistent with the reassembly logic of the second client front-end device. This reduces data errors throughout the entire process from transmission to reassembly, ensures that the image file is consistent with the original file, lays an accurate data foundation for subsequent format conversion, and reduces disputes over file validity.

[0114] Taking advantage of the local area network gateway's support for the IP fax standard, the reconstructed image file is converted into intermediate data to ensure protocol compatibility with the gateway. At the same time, the local area network gateway decodes the intermediate data into PSTN analog signals, realizing seamless connection between the IP network (session border controller) and the PSTN network (second fax machine), adapting to the CPE-SBC-gateway-PSTN architecture and expanding the application scenarios of the technology.

[0115] The session boundary controller and the local area network gateway are deployed in the core network IDC room, ensuring controllable IP link transmission quality and reducing the impact of packet loss and latency. Furthermore, the second fax machine prints page by page / line by line, matching the sending rhythm, which not only continues the real-time interactive fax experience but also relies on the advantages of the core network to ensure stable transmission, further improving the success rate of fax services under the VoIP network.

[0116] like Figure 4 As shown, in an optional embodiment of the present invention, in step 142, the first client front-end device transmits the plurality of data packets to the second fax machine in real time via the Internet Session Protocol link, through the session boundary controller and the local area network gateway, via the switched telephone network, including:

[0117] Step 1423: The first client front-end device converts the multiple data packets into intermediate fax data via the Internet Session Protocol link, through the session boundary controller and the unified cloud platform, and then into switched telephone network signals via the local area network gateway, and sends them to the second fax machine through the switched telephone network. Specifically, after receiving the data packets and verifying their integrity, the session boundary controller does not directly convert them, but forwards the data packets to the unified cloud platform (UC server) in real time through the core network IP link (located in the same data center as the unified cloud platform, ensuring high reliability). During the forwarding process, the unique identifier of the image unit is retained to ensure accurate subsequent reassembly.

[0118] After receiving the data packet, the unified cloud platform reassembles it into an image file according to the identifier, and then converts it into intermediate fax data in G.711Codec format (G.711 is a common encoding for PSTN voice / fax).

[0119] The unified cloud platform sends G.711 format intermediate data to the local area network gateway, which decodes it into switched telephone network signals (analog fax signals), and then transmits it to the second fax machine via the PSTN network. The second fax machine receives and prints the data in real time, and at the same time sends back a successful reception signal via the PSTN (which is transmitted back to the first client front-end device via the local area network gateway, the unified cloud platform, and the session boundary controller).

[0120] In this embodiment, the unified cloud platform converts the reconstructed image file into intermediate data in G.711Codec format. This format is a common encoding for PSTN voice / fax, covering more network device scenarios and improving the applicability of the technology in different gateway environments.

[0121] The session boundary controller is located in the same data center as the unified cloud platform. It forwards data packets through the core network IP link, ensuring controllable link transmission quality and effectively avoiding common IP network issues such as packet loss and latency. Furthermore, it retains the unique identifier of the image unit during forwarding, ensuring that the unified cloud platform can accurately reassemble image files and guaranteeing data stability and accuracy throughout the entire process from transmission to reassembly.

[0122] The second fax machine transmits the successful reception signal back to the first client front-end device via the PSTN, through the local area network gateway, unified cloud platform, and session boundary controller, forming a closed-loop status quo. The first client front-end device can obtain the fax reception status in real time, facilitating progress synchronization with the first fax machine and providing a basis for subsequent troubleshooting. It also maintains the real-time fax interaction experience and reduces user confusion caused by missing feedback.

[0123] Example 1

[0124] An administrative staff member of a company sent a two-page contract document to a partner's second fax machine via the first fax machine. The contract documents corresponded to three scenarios: an end-to-end network model, a scenario with SBC participation, and a scenario with both SBC and local area network gateway participation.

[0125] The first fax machine is a traditional analog fax machine capable of scanning documents page by page. The first client front-end device is physically connected to the first fax machine via a subscriber line interface, using PSTN interaction, with an IP address of 192.168.3.20. In an end-to-end scenario, the second fax machine is connected to the second client front-end device (IP address 192.168.4.20) via a subscriber line interface. In a scenario with a session boundary controller, it accesses the Public Switched Telephone Network (PSTN), with numbers ranging from 000 to 00000000. The session boundary controller is deployed in the cloud, with an IP address of 10.2.0.8. The unified cloud platform (UC server) and the session boundary controller are both located in the core network IDC data center, with an IP address of 10.2.0.9.

[0126] A method for real-time relay transmission of fax data includes:

[0127] End-to-end network model:

[0128] Step 21, Call connection and fax data reception:

[0129] An administrative staff member operates the first fax machine and dials (to the logically associated number of the second client front-end device) through the subscriber line interface to initiate a call to the first client front-end device. The first client front-end device generates a SIP-Invite signaling message and sends it to the second client front-end device (IP address 192.168.4.20) via the IP network (Internet Session Protocol link). After receiving the signaling message, the second client front-end device returns a SIP-180 Ring signaling message, triggering the second fax machine to ring. After hearing the ringing, the staff member of the cooperating unit operates the second fax machine to pick up the phone. The second client front-end device then sends a SIP-200 OK signaling message. After receiving this signaling message, the first client front-end device confirms that the call has been established.

[0130] The first fax machine scans two pages of a contract document (page 1 is the contract cover page, and page 2 is the signature page) one by one. After scanning each page, it immediately sends an analog image signal to the first client front-end device through the user line interface. This signal contains the document's light and dark pixel information, such as black pixels for text and white pixels for blank areas. The first client front-end device receives the signal in real time, with the receiving rhythm synchronized with the scanning rhythm of the first fax machine (receiving one page signal every 2 seconds), without data backlog.

[0131] Step 22: The first client-side front-end device converts the fax data into an image file.

[0132] The first client-side front-end device performs discrete sampling on the received analog image signal at a set sampling frequency, acquiring the instantaneous amplitude of the signal every 1 / 9600 seconds, and converting the continuously changing analog waveform into discrete electrical signal data. During the sampling process, the first client-side front-end device filters high-frequency noise (interference signals with frequencies higher than 4800Hz) in the signal through a low-pass filter to ensure that the electrical signal data accurately reflects the document pixel information.

[0133] The first client-side front-end device maps discrete electrical signal data (voltage values) to 256 preset quantization levels, each level corresponding to a fixed voltage range (e.g., 0~0.2V corresponds to one level). Subsequently, the quantization level corresponding to each electrical signal data is converted into an 8-bit binary number to form a continuous binary sequence (digital signal stream), and a parity check bit is added to the digital signal stream (e.g., the parity bit of the first page of the signal stream is 0) to detect potential voltage value misjudgment problems during the quantization process and ensure the accuracy of the digital signal stream.

[0134] The first client-side front-end device identifies the MH encoding format used in the digital signal stream, decodes it according to the MH encoding rules, and restores the code elements representing 150 consecutive white pixels and 80 consecutive black pixels in the signal stream to the actual pixel length, thus obtaining the pixel sequence of each line. After integrating all the line data of the two-page document, it generates structured digital fax information, which includes the pixel matrix of each page (the pixel matrix of the first page is 1728×2048), resolution (204×98dpi), page size (A4), and total number of pages (2 pages).

[0135] The first client-side front-end device preferentially selects TIFF format to encapsulate digital fax information, writes the TIFF file header (byte order identifier II, version number 0x002A, first IFD offset address 0x00000008), creates IFDs for the two pages of the document, and records the page width (1728), height (2048), 1 bit depth (black and white binary), and T.4 compression method for each IFD. Then, it writes the compressed pixel data according to the IFD offset address, associates the two pages of data through the IFD linked list, and generates a multi-page TIFF file (named contract_2pages.tif).

[0136] Step 23: Decompose the image file and package it into a data packet:

[0137] The first client-side front-end device decomposes the multi-page TIFF file into two image units page by page, with each unit containing the complete data of the corresponding page; a unique identifier is added to the first image unit (type 0x01 indicating page by page, total number of pages 2, current page number 1, data length 35KB), and an identifier is added to the second image unit (type 0x01, total number of pages 2, current page number 2, data length 32KB) to ensure that the second client-side front-end device can reassemble the data according to the identifier;

[0138] The first client front-end device uses the TFTP protocol to encapsulate image units, adds a TFTP data frame header (opcode 0x0003, block numbers 1 and 2 respectively, the block number is associated with the image unit sequence number) to each image unit, and then encapsulates a UDP header (source port 69, destination port 69) and an IP header (source IP 192.168.3.20, destination IP 192.168.4.20, protocol type = UDP), finally obtaining 2 data packets;

[0139] Step 24, First client front-end device - Second client front-end device - Second fax machine:

[0140] After the first client-side device completes the encapsulation of a data packet, it immediately sends it to the second client-side device via the Internet Session Protocol link. The sending interval is synchronized with the scanning rhythm of the first fax machine (one data packet is sent every 2 seconds). At the same time, the first client-side device adds a unique identifier to each data packet and initiates a timeout retransmission mechanism. If no acknowledgment signal is received from the second client-side device within 500ms, the data packet is retransmitted (in this scenario, the network is stable and no retransmission is triggered).

[0141] After receiving the data packet, the second client front-end device first verifies the integrity of the network layer (checks the IP header checksum and UDP sequence number) and filters out corrupted data packets; then it parses the transport layer data, extracts the image unit and its unique identifier, and confirms the integrity of the unit data through the CRC check code; since the image unit is a page-by-page type (0x01), the second client front-end device sorts the data according to the total number of pages 2 and the current page number 1 and 2, and concatenates the two units into complete single-page data respectively. After accumulating until the total number of pages reaches the target, it is packaged into a multi-page TIFF file that is consistent with the original file of the first client front-end device.

[0142] The second client front-end device reads the metadata (resolution 204×98dpi, page size A4) and pixel matrix of the reconstructed TIFF file and restores the digital fax information consistent with step 123 of the first client front-end device;

[0143] The second client front-end device converts digital fax information into analog fax signals (switched telephone network signals); following a page-by-page rhythm, it first converts the pixel matrix of the first page into an MH-coded modulation signal and sends it to the second fax machine through the subscriber line interface; after sending, it waits for the confirmation signal returned by the second fax machine (indicating that the first page was successfully received) before sending the second page signal, ensuring that it matches the scanning rhythm of the first fax machine;

[0144] Each time the second client front-end device receives an image unit, it returns unit sequence number 1 + successful reception unit sequence number 2 + successful reception to the first client front-end device via SIPINFO signaling; after completing the reconstruction of 2 pages, it returns a page completion signal (SIPMESSAGE signaling), and the first client front-end device uses this to provide progress feedback to the first fax machine through the subscriber line interface (with short tones indicating that page 1 and page 2 have been sent successfully); after all transmissions are completed, the second client front-end device sends SIPBYE signaling, the first client front-end device responds with confirmation, both parties release the session link, and the second fax machine prints out the 2-page complete contract document;

[0145] Session boundary controllers are involved.

[0146] Steps 31-33 are consistent with the end-to-end scenario:

[0147] The first client front-end device completes the encapsulation of two data packets. The destination IP of the data packets is changed to the IP address of the session boundary controller (10.2.0.8). The remaining steps (call setup, data sampling and quantization, image file encapsulation, and cell decomposition) are exactly the same as in scenario 1.

[0148] Step 34: First client front-end device - session boundary controller - local area network gateway - second fax machine;

[0149] The first client-side front-end device reuses the Internet Session Protocol link used during call establishment (which has been confirmed as connected via SIP-2000k). Following the principle of immediate transmission per unit, each data packet generated is immediately sent to the session boundary controller via the IP network, with the transmission rhythm synchronized with the first fax machine's page-by-page scanning (one packet every 2 seconds). The first client-side front-end device adds a unique identifier to the data packet. If it does not receive the SIPINFO acknowledgment signal from the session boundary controller within 500ms, it retransmits the data packet (in this scenario, there is no packet loss, so retransmission is unnecessary).

[0150] After receiving the data packet, the session boundary controller first verifies the integrity of the IP / TCP / UDP layer (checking the checksum and sequence number) and filters out corrupted packets. Then, it parses out the image unit and its unique identifier (type 0x01, total number of pages 2, page number 1 / 2). After confirming the integrity of the unit through CRC check, it concatenates the pages into a multi-page TIFF file (consistent with the file generated by the first client's front-end device). The session boundary controller encapsulates the pixel matrix, resolution, and other information of the TIFF file into a data frame (containing control signaling and image data blocks) to form intermediate fax data.

[0151] The session boundary controller transmits intermediate data to the local area network gateway in real time via the IP link of the core network IDC room, and simultaneously synchronizes the data transmission progress (e.g., the first page of intermediate data has been sent) with the local area network gateway via SIP signaling. After receiving the intermediate data, the local area network gateway decodes it into an analog fax signal supported by the PSTN network, and then accesses the PSTN network via an E1 trunk link. The analog signal is transmitted to the telephone line (number 000-00000000) where the second fax machine is located via the PSTN network, triggering the second fax machine's receiving process. The second fax machine prints two pages of the contract document one by one, with the printing rhythm synchronized with the sending rhythm.

[0152] Session boundary controllers and local area network gateways are involved.

[0153] Steps 41-43 are consistent with the end-to-end scenario:

[0154] The two data packets generated by the first client front-end device still have the same destination IP as the session border controller 10.2.0.8, and the rest of the steps remain unchanged;

[0155] Step 44, the Session Border Controller - Unified Cloud Platform - Local Area Network Gateway - Second Fax Machine:

[0156] After receiving and verifying the integrity of the data packet, the session boundary controller does not directly convert the data. Instead, it forwards the data packet to the unified cloud platform (IP address 10.2.0.9) in real time through the highly reliable IP link of the core network IDC data center (located in the same data center as the unified cloud platform, with a latency of <10ms). During the forwarding process, the unique identifier of the image unit (type 0x01, page number 1 / 2, etc.) is retained to ensure accurate subsequent reassembly.

[0157] The unified cloud platform converts the data into intermediate fax data: After receiving the data packet, the unified cloud platform reassembles it into a multi-page TIFF file according to the unique identifier of the image unit; the unified cloud platform converts the TIFF file into intermediate fax data in G.711 Codec format (G.711 is a common voice / fax codec for PSTN networks, adapted to local area network gateways).

[0158] The unified cloud platform-local area network gateway-second fax machine sequence works as follows: The unified cloud platform sends G.711 format intermediate data to the local area network gateway. After receiving the data, the local area network gateway decodes it into an analog fax signal (switched telephone network signal) and then connects it to the PSTN network via an E1 trunk link. The signal is transmitted to the second fax machine via the PSTN network, where it receives and prints two pages of the contract document in real time. Simultaneously, the second fax machine sends a successful reception signal back through the PSTN network. This signal is transmitted back to the first client front-end device via the local area network gateway, the unified cloud platform, and the session boundary controller. The first client front-end device then sends a transmission completion prompt tone to the first fax machine through the subscriber line interface.

[0159] This invention receives, converts, and transmits fax data in real time, page by page / line by line, with the sending rhythm synchronized with the fax machine scanning. This avoids cache backlog and delays, restores the real-time interactive characteristics of traditional faxes, solves the feedback delay problem of the store-and-forward mode, and is suitable for scenarios with high real-time requirements, such as doctor's prescriptions and legal documents.

[0160] From signal processing (low-pass filtering, quantization verification) and unit splitting (unique identifier + CRC check) to timeout retransmission during transmission and dual verification at the network and data layers at the receiving end, the entire process reduces the risk of errors and data loss; the reverse reconstruction logic ensures that the image file is consistent with the original, reducing disputes over file validity.

[0161] It supports two network models: end-to-end (CPE to CPE) and network with SBC, and is compatible with different IP protocols (TFTP / FTP / HTTP), breaking through network architecture and device limitations and expanding application scenarios.

[0162] Unitized transmission enables partial retransmission, reducing bandwidth consumption; end-to-end status feedback (SIP signaling) forms a closed loop, facilitating real-time monitoring of progress and troubleshooting; relying on the high-reliability link of the core network, it improves the success rate of fax services under VoIP networks.

[0163] like Figure 5 As shown, this embodiment of the invention also provides a real-time relay transmission device for fax data, applied to a first client front-end device, the first client front-end device being communicatively connected to a first fax machine, the device 50 comprising:

[0164] The transceiver module 51 is used to receive fax data sent by the first fax machine after the call between the first fax machine and the second fax machine is connected.

[0165] Processing module 52 is used to convert the fax data into an image file; decompose the image file into multiple image units, encapsulate them through Internet Protocol, and obtain multiple data packets;

[0166] The transceiver module 51 is also used to send the multiple data packets to the second fax machine in real time via an Internet Session Protocol link.

[0167] Optionally, the processing module 52 is further configured to:

[0168] Discrete sampling is performed on the analog image signal of the fax data to obtain discrete electrical signal data;

[0169] The electrical signal data is quantized to obtain a digital signal stream;

[0170] The digital signal stream is decoded to obtain digital fax information;

[0171] The digital fax information is encapsulated into an image file.

[0172] Optionally, the processing module 52 is further configured to:

[0173] The image file is decomposed into multiple image units, and a unique identifier is added to each image unit;

[0174] The image unit is encapsulated using Internet Protocol to obtain multiple data packets.

[0175] Optionally, the transceiver module 51 is further configured to:

[0176] The multiple data packets are transmitted in real time to the second fax machine via the Internet Session Protocol link through the second client front-end device.

[0177] Optionally, the transceiver module 51 is further configured to:

[0178] The multiple data packets are transmitted in real time to the second fax machine via the Internet Session Protocol link, through the session boundary controller and the local area network gateway, and via the switched telephone network.

[0179] Optionally, the transceiver module 51 is further configured to:

[0180] The multiple data packets are transmitted via an Internet Session Protocol link and then converted into intermediate fax data by the session boundary controller.

[0181] The intermediate fax data is converted into switched telephone network (STN) signals by the session boundary controller and the local area network gateway, and then sent to the second fax machine via the STN.

[0182] Optionally, the transceiver module 51 is further configured to:

[0183] The multiple data packets are transmitted via Internet Session Protocol (ISP) links, converted into intermediate fax data by the session boundary controller and unified cloud platform, converted into switched telephone network (STN) signals by the local area network gateway, and sent to the second fax machine via the STN.

[0184] It should be noted that this device is a device corresponding to the method on the first client-side front-end device described above. All implementation methods in the above method embodiments are applicable to this embodiment and can achieve the same technical effect.

[0185] This invention also provides a real-time relay transmission system for fax data, comprising: a first client front-end device and at least one relay transmission device, wherein the first client front-end device is communicatively connected to a first fax machine;

[0186] After the call between the first fax machine and the second fax machine is connected, the first client front-end device receives the fax data sent by the first fax machine.

[0187] The first client-side front-end device converts the fax data into an image file;

[0188] The first client-side device decomposes the image file into multiple image units, which are then encapsulated using the Internet Protocol to obtain multiple data packets;

[0189] The first client front-end device sends the multiple data packets to the second fax machine in real time through the Internet Session Protocol link of at least one relay transmission device.

[0190] Optionally, the first client-side front-end device sends the multiple data packets to the second client-side front-end device in real time via an Internet Session Protocol link, and the second client-side front-end device then sends them to the second fax machine; or

[0191] The first client front-end device sends the multiple data packets to the session boundary controller in real time via the Internet Session Protocol link; the session boundary controller then sends the multiple data packets to the second fax machine via the local area network gateway through the switched telephone network.

[0192] It should be noted that this system is a system corresponding to the method of the real-time relay transmission system described above. All implementation methods in the above method embodiments are applicable to this embodiment and can achieve the same technical effect.

[0193] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for real-time relay transmission of facsimile data, characterized by, The method is applied to a first client front-end device, the first client front-end device is in communication connection with a first fax machine, and the method comprises the following steps: After the first fax machine and the second fax machine are called and connected, the first client front-end device receives fax data sent by the first fax machine; The first client front-end device converts the fax data into an image file; The first client front-end device decomposes the image file into multiple image units, encapsulates the image units through an Internet protocol to obtain multiple data packets, and sends the multiple data packets to the second fax machine through an Internet session protocol link in real time; The first client front-end device decomposes the image file into multiple image units, encapsulates the image units through an Internet protocol to obtain multiple data packets, and sends the multiple data packets to the second fax machine through an Internet session protocol link in real time, and the method comprises the following steps: The image file is decomposed into multiple image units, and a unique identifier is added to each image unit; specifically, the multiple-page image file is decomposed into image units page by page, each unit contains complete data of a single page, and a unique identifier is added; The image units are encapsulated through an Internet protocol to obtain multiple data packets; The first client front-end device decomposes the image file into multiple image units, encapsulates the image units through an Internet protocol to obtain multiple data packets, and sends the multiple data packets to the second fax machine through an Internet session protocol link in real time, and the method comprises the following steps: ​ The first client front-end device sends the multiple data packets to the second fax machine in real time through an Internet session protocol link via a second client front-end device; specifically, the first client front-end device sends the data packets to the second client front-end device through the Internet session protocol link immediately after completing the encapsulation of one image unit, and the sending interval is synchronized with the scanning rhythm of the first fax machine; after receiving the data packets, the second client front-end device first verifies the integrity of the network layer and filters damaged data packets; then, the second client front-end device parses the transport layer data, extracts the image unit and its unique identifier, and verifies whether the unit data is complete through a cyclic redundancy check (CRC) code; if it is a page-by-page unit, the second client front-end device sorts the same page units according to the total number of pages and the current page number, splices the single-page data into complete single-page data, and encapsulates the data into a multi-page image file after accumulating to the total number of pages; if it is a streaming unit, the second client front-end device sorts the single-row pixel data according to the total number of rows and the current row number, splices the single-row pixel data in sequence, and encapsulates the data into a single-page image file after accumulating to the total number of rows; the second client front-end device reads the metadata and pixel matrix of the reorganized image file to restore the digital fax information; the second client front-end device converts the digital fax information into a switched telephone network signal, and if it is a multi-page image file, converts each page of pixel matrix into an analog signal according to the page-by-page rhythm, sends the signal to the second fax machine through a subscriber line interface, waits for an acknowledgement signal from the second fax machine after sending one page, and then sends the next page to match the page-by-page scanning rhythm of the first fax machine; if it is a single-page long document, converts each row of pixel data into an analog signal according to the row-by-row rhythm and sends the signal in real time to synchronize with the row-by-row scanning rhythm of the first fax machine; the second client front-end device feeds back the status to the first client front-end device at the following nodes to form a closed loop: after receiving each image unit, the second client front-end device returns the unit number and the reception status through signaling to trigger the first client front-end device to retransmit; after completing the reorganization of one page / one whole page, the second client front-end device returns a page completion signal, and the first client front-end device feeds back the sending progress to the first fax machine accordingly; after completing the entire transmission, the second client front-end device sends a response signaling, the first client front-end device responds to the confirmation, and both sides release the session link to complete the entire fax process.

2. The real-time relay transmission method of facsimile data according to claim 1, wherein, The first client front-end device converts the fax data into an image file, including: discretely sampling the analog image signal of the fax data to obtain discrete electrical signal data; quantizing the electrical signal data to obtain a digital signal stream; decoding the digital signal stream to obtain digital fax information; encapsulating the digital fax information into an image file.

3. The real-time relay transmission method of facsimile data according to claim 1, wherein, The first client front-end device sends the multiple data packets to the second fax machine in real time through an Internet session protocol link via a session border controller and a local area network gateway through a switched telephone network, including: The first client front-end device converts the multiple data packets into intermediate fax data via the session border controller through the Internet session protocol link. The first client front-end device converts the intermediate fax data into exchange telephone network signals via the session border controller and the local area network gateway, and transmits the intermediate fax data to the second fax machine through the exchange telephone network.

4. The real-time relay transmission method of facsimile data as claimed in claim 1, wherein, The first client front-end device converts the multiple data packets into intermediate fax data via the session border controller and the local area network gateway, and transmits the intermediate fax data to the second fax machine through the exchange telephone network in real time. The first client front-end device converts the multiple data packets into intermediate fax data via the session border controller and the local area network gateway, and transmits the intermediate fax data to the second fax machine through the exchange telephone network in real time.

5. A real-time relay apparatus for facsimile data, characterized by comprising: The application is applied to a first client front-end device, which is in communication connection with a first fax machine. The transceiving module is configured to receive fax data transmitted by the first fax machine after the call of the first fax machine and the second fax machine is connected; The processing module is configured to convert the fax data into an image file, decompose the image file into multiple image units, and obtain multiple data packets by encapsulating the multiple image units via an Internet protocol. The transceiving module is further configured to transmit the multiple data packets to the second fax machine in real time via an Internet session protocol link. The first client front-end device converts the image file into multiple image units, encapsulates the multiple image units via an Internet protocol, and obtains multiple data packets, including: The image file is decomposed into multiple image units, and a unique identifier is added to each image unit. Specifically, the multiple-page image file is decomposed into image units page by page, each unit contains complete data of a single page, and a unique identifier is added. The image units are encapsulated via an Internet protocol to obtain multiple data packets. The first client front-end device converts the multiple data packets into intermediate fax data via the session border controller and the local area network gateway, and transmits the intermediate fax data to the second fax machine through the exchange telephone network in real time. The first client front-end device sends the multiple data packets to the second fax machine in real time through an Internet session protocol link via a second client front-end device; specifically, the first client front-end device sends the data packets to the second client front-end device through the Internet session protocol link immediately after completing the encapsulation of one image unit, and the sending interval is synchronized with the scanning rhythm of the first fax machine; after receiving the data packets, the second client front-end device first verifies the integrity of the network layer and filters damaged data packets; then, the second client front-end device parses the transport layer data, extracts the image unit and its unique identifier, and verifies whether the unit data is complete through a cyclic redundancy check (CRC) code; if it is a page-by-page unit, the second client front-end device sorts the same page units according to the total number of pages and the current page number, splices the single-page data into complete single-page data, and encapsulates the data into a multi-page image file after accumulating to the total number of pages; if it is a streaming unit, the second client front-end device sorts the single-row pixel data according to the total number of rows and the current row number, splices the single-row pixel data in sequence, and encapsulates the data into a single-page image file after accumulating to the total number of rows; the second client front-end device reads the metadata and pixel matrix of the reorganized image file to restore the digital fax information; the second client front-end device converts the digital fax information into a switched telephone network signal, and if it is a multi-page image file, converts each page of pixel matrix into an analog signal according to the page-by-page rhythm, sends the signal to the second fax machine through a subscriber line interface, waits for an acknowledgement signal from the second fax machine after sending one page, and then sends the next page to match the page-by-page scanning rhythm of the first fax machine; if it is a single-page long document, converts each row of pixel data into an analog signal in real time according to the row-by-row rhythm to synchronize with the row-by-row scanning rhythm of the first fax machine; the second client front-end device feeds back the status to the first client front-end device at the following nodes to form a closed loop: after receiving each image unit, returns the unit number and the reception status through signaling to trigger the first client front-end device to retransmit; after completing the reorganization of one page / one whole page, returns a page completion signal, and the first client front-end device feeds back the sending progress to the first fax machine accordingly; after completing the entire transmission, the second client front-end device sends a response signaling, the first client front-end device responds to the confirmation, and both sides release the session link to complete the entire fax process.

6. A real-time relay transmission system of facsimile data, characterized by, It comprises: a first client front-end device and at least one relay transmission device, wherein the first client front-end device is communicatively connected with a first fax machine; after the call between the first fax machine and a second fax machine is connected, the first client front-end device receives the fax data sent by the first fax machine; the first client front-end device converts the fax data into an image file; the first client front-end device decomposes the image file into multiple image units, encapsulates the image units through an Internet protocol to obtain multiple data packets, and sends the data packets to the second fax machine in real time through an Internet session protocol link of the at least one relay transmission device; wherein the first client front-end device decomposes the image file into multiple image units, encapsulates the image units through an Internet protocol to obtain multiple data packets, and sends the data packets to the second fax machine in real time through an Internet session protocol link of the at least one relay transmission device, comprising: ​ The image file is decomposed into multiple image units, and a unique identifier is added to each image unit; specifically, the multiple-page image file is decomposed into image units page by page, each unit containing complete data of a single page, and a unique identifier is added; The image units are encapsulated through an Internet protocol to obtain multiple data packets; The first client front-end device sends the multiple data packets to the second fax machine in real time through an Internet session protocol link, including: The first client front-end device sends the multiple data packets to the second fax machine in real time through an Internet session protocol link via the second client front-end device; specifically, the first client front-end device immediately sends to the second client front-end device through an Internet session protocol link after completing the encapsulation of each image unit, and the sending interval is synchronized with the scanning rhythm of the first fax machine; after receiving the data packets, the second client front-end device first verifies the network layer integrity and filters damaged data packets; then it analyzes the transport layer data, extracts the image units and their unique identifiers, and verifies whether the unit data is complete through a cyclic redundancy check (CRC) code; if it is a page-by-page unit, the second client front-end device sorts the same-page units according to the total number of pages and the current page number, splices them into complete single-page data, and accumulates them until the total number of pages reaches the standard, then encapsulates them into a multiple-page image file; if it is a streaming unit, it sorts the single-row pixel data according to the total number of rows and the current row number, splices them in order, and accumulates them until the total number of rows reaches the standard, then encapsulates them into a single-page image file; the second client front-end device reads the metadata and pixel matrix of the reorganized image file to restore the digital fax information; the second client front-end device converts the digital fax information into a switched telephone network signal, and if it is a multiple-page image file, it converts each page of pixel matrix into an analog signal according to the page-by-page rhythm and sends it to the second fax machine through the subscriber line interface, waits for the confirmation signal from the second fax machine after sending one page, and then sends the next page, matching the page-by-page scanning rhythm of the first fax machine; if it is a single-page long document, it converts each row of pixel data into an analog signal in real time according to the row-by-row rhythm and sends it in synchronization with the row-by-row scanning rhythm of the first fax machine; the second client front-end device feeds back the status to the first client front-end device at the following nodes to form a closed loop: after receiving each image unit, it returns the unit number + reception status through signaling, which is used by the first client front-end device to trigger retransmission; after completing the reorganization of a page / whole page, it returns a page completion signal, based on which the first client front-end device feeds back the sending progress to the first fax machine; after completing the entire transmission, the second client front-end device sends a response signaling, the first client front-end device responds to the confirmation, and both sides release the session link, completing the entire fax process.

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