Real-time facsimile transmission over digital networks

Abstract

Providing facsimile communications in a system wherein an originating facsimile terminal equipment (FTE) connects to an intermediate digital network of unknown and unpredictable delay via an originating facsimile interface unit (FIU) and wherein a destination FTE connects to the network via a destination FIU. The originating FTE sends data to the destination FTE via the originating FIU. The originating FIU sends the data to the destination FIU. While the destination FIU is waiting for data from the originating FTE, the destination FIU sends made-up data to the destination FTE to prevent protocol timeouts of the destination FTE. The FTEs operate under the G3 protocol. The made up data is either fill data or stall data, depending on the amount of data accumulated at the destination FIU and on the types of network delays.

What is claimed:  
     
         1 . In a system wherein an originating facsimile terminal equipment (FTE) which operates according to the G3 protocol connects to an intermediate digital network of unknown and unpredictable delay via an originating facsimile interface unit (FIU) and wherein a destination FTE which operates according to the G3 protocol and connects to the network via a destination FIU, a method of providing facsimile communications comprising: 
 (a) the originating FTE sending data to the destination FTE via the originating FIU and the destination FIU;    (b) the originating FIU sending the data to the destination FIU;    (c) while the destination FIU is waiting for data from the originating FTE, the destination FIU sending a made-up data to the destination FTE to prevent protocol timeouts of the destination FTE, wherein the destination FIU sends made-up data to the destination FTE until the destination FIU has accumulated some data from the originating FTE;    (d) the originating FTE, at the end of sending a page of data, sending an end-of-page signal to the destination FTE via the originating FIU;    (e) the originating FIU delaying acknowledgment to the originating FTE of the end-of-page signal; and    (f) in response to the delayed acknowledgment, the originating FTE sending an another end-of-page signal to the destination FTE via the originating FIU, thereby allowing the destination FIU and the destination FTE to complete their end-of-page protocol, wherein: 
 (i) the data being sent by the originating FTE is scan-line data of a document being sent, and wherein the made-up data comprises data which has a valid format and which was not part of the original document,  
 (ii) the destination FIU sends the made-up data to the destination FTE when the destination FIU has not received a scan line from the originating FIU, and wherein the made-up data comprises a valid scan line,  
 (iii) the destination FIU sends the made-up data to the destination FTE when the destination FIU has received at least some of a scan line from the originating FIU,  
 (iv) the made-up data comprises some of the received scan line and additional data,  
 (v) the kind of made-up data sent to the destination FTE depends on the number of complete, unprinted scan lines that have been received by the destination FIU over the network; and  
 (vi) the sending made-up data comprises: 
 (1) when the destination FIU detects a slowdown in the arrival of data over the network, sending filled lines to the destination FTE, and  
 (2) when the destination FIU detects unexpected delays in the arrival of data, sending stalling lines to the destination FTE.  
 
   
     
     
         2 . In a system wherein an originating facsimile terminal equipment (FTE) connects to an intermediate digital network via an originating facsimile interface unit (FIU) and wherein a destination FTE connects to the network via a destination FIU, a method of providing facsimile communications comprising: 
 (a) the originating FTE sending data to the destination FTE via the originating FIU and the destination FIU;    (b) the originating FIU sending the data to the destination FIU; and    (c) while the destination FIU is waiting for data from the originating FTE, the destination FIU sending a made-up data to the destination FTE to prevent protocol timeouts of the destination FTE.    
     
     
         3 . A method as in    claim 2    wherein the data being sent by the originating FTE is scan-line data of a document being sent, and wherein the made-up data comprises data which has a valid format and which was not part of the original document.  
     
     
         4 . A method as in    claim 3    wherein the destination FIU sends the made-up data to the destination FTE when the destination FIU has not received a scan line from the originating FIU, and wherein the made-up data comprises a valid scan line.  
     
     
         5 . A method as in    claim 4    wherein the destination FIU sends made-up data to the destination FTE until the destination FIU has accumulated some data from the originating FTE.  
     
     
         6 . A method as in    claim 4    wherein the destination FIU sends made-up data to the destination FTE until the destination FIU receives an all-white scan line, the method further comprising, when the destination FIU receives an all-white scan line, sending to the destination FTE additional white scan lines.  
     
     
         7 . A method as in    claim 3    wherein the destination FIU sends the made-up data to the destination FTE when the destination FIU has received at least some of a scan line from the originating FIU, and wherein the made-up data comprises some of the received scan line and additional data.  
     
     
         8 . A method as in    claim 3    wherein the kind of made-up data sent to the destination FTE depends on the number of complete, unprinted scan lines that have been received by the destination FIU over the network.  
     
     
         9 . A method as in    claim 8    wherein the sending made-up data comprises: 
 (a) when the destination FIU detects a slowdown in the arrival of data over the network, sending filled lines to the destination FTE, and  
 (b) when the destination FIU detects unexpected delays in the arrival of data, sending stalling lines to the destination FTE.  
 
     
     
         10 . A method as in    claim 2    further comprising: 
 (d) the originating FTE, at the end of sending a page of data, sending an end-of-page signal to the destination FTE via the originating FIU;  
 (e) the originating FIU delaying acknowledgment to the originating FTE of the end-of-page signal; and  
 (f) in response to the delayed acknowledgment, the originating FTE sending an another end-of-page signal to the destination FTE via the originating FIU, thereby allowing the destination FIU and the destination FTE to complete their end-of-page protocol.  
 
     
     
         11 . A method as in    claim 2    further comprising, in an error correcting mode (ECM) in which page data is broken up into frames, the destination FIU 
 (d) packaging into frames all page data sent to be sent to the destination FTE;  
 (e) sending all page data to the destination FTE as the packaged frames;  
 (f) keeping a copy of each packaged frame sent to the destination FTE; and  
 (e) in response to a request from the destination FTE for retransmission of a frame, sending a copy of the requested frame.  
 
     
     
         12 . A method as in    claim 11    wherein the destination FIU keeps a copy of each packaged frame sent to the destination FTE until the frame is acknowledged by the destination FTE.  
     
     
         13 . In a system wherein an originating facsimile terminal equipment (FTE) connects to an intermediate digital network via an originating facsimile interface unit (FIU) and wherein a destination FTE connects to the network via a destination FIU, a method of receiving a facsimile communication comprising, by the destination FIU: 
 (a) receiving data from the originating FTE; and    (b) while waiting for data from the originating FTE, sending a made-up data to the destination FTE to prevent protocol timeouts of the destination FTE.    
     
     
         14 . A method as in    claim 13    wherein the data being sent by the originating FTE is scan-line data of a document being sent, and wherein the made-up data comprises data which has a valid format and which was not part of the original document.  
     
     
         15 . A method as in    claim 14    wherein the destination FIU sends the made-up data to the destination FTE when the destination FIU has not received a scan line from the originating FIU, and wherein the made-up data comprises a valid scan line.  
     
     
         16 . A method as in    claim 15    wherein the destination FIU sends made-up data to the destination FTE until the destination FIU has accumulated some data from the originating FTE.  
     
     
         17 . A method as in    claim 15    wherein the destination FIU sends made-up data to the destination FTE until the destination FIU receives an all-white scan line, the method further comprising, when the destination FIU receives an all-white scan line, sending to the destination FTE additional white scan lines.  
     
     
         18 . A method as in    claim 14    wherein the destination FIU sends the made-up data to the destination FTE when the destination FIU has received at least some of a scan line from the originating FIU, and wherein the made-up data comprises some of the received scan line and additional data.  
     
     
         19 . A method as in    claim 14    wherein the kind of made-up data sent to the destination FTE depends on the number of complete, unprinted scan lines that have been received by the destination FIU over the network.  
     
     
         20 . A method as in    claim 19    wherein the sending made-up data comprises: 
 (a) when the destination FIU detects a slowdown in the arrival of data over the network, sending filled lines to the destination FTE, and  
 (b) when the destination FIU detects unexpected delays in the arrival of data, sending stalling lines to the destination FTE.  
 
     
     
         21 . A method of receiving a facsimile communication at a destination facsimile terminal equipment (FTE) from an originating FTE via an intermediate digital network, wherein the destination FTE connects to the network via a destination FIU, the method comprising, by the destination FIU: 
 (a) receiving data from the originating FTE; and    (b) while waiting for data from the originating FTE, sending a made-up data to the destination FTE to prevent protocol timeouts of the destination FTE.    
     
     
         22 . A method as in    claim 21    wherein the data being sent by the originating FTE is scan-line data of a document being sent, and wherein the made-up data comprises data which has a valid format and which was not part of the original document.  
     
     
         23 . A method as in    claim 22    wherein the destination FIU sends the made-up data to the destination FTE when the destination FIU has not received a scan line from the originating FIU, and wherein the made-up data comprises a valid scan line.  
     
     
         24 . A method as in    claim 22    wherein the destination FIU sends made-up data to the destination FTE until the destination FIU has accumulated some data from the originating FTE.  
     
     
         25 . A method as in    claim 22    wherein the destination FIU sends made-up data to the destination FTE until the destination FIU receives an all-white scan line, the method further comprising, when the destination FIU receives an all-white scan line, sending to the destination FTE additional white scan lines.  
     
     
         26 . A method as in    claim 23    wherein the destination FIU sends the made-up data to the destination FTE when the destination FIU has received at least some of a scan line from the originating FIU, and wherein the made-up data comprises some of the received scan line and additional data.  
     
     
         27 . A method as in    claim 24    wherein the kind of made-up data sent to the destination FTE depends on the number of complete, unprinted scan lines that have been received by the destination FIU over the network.  
     
     
         28 . A method as in    claim 23    wherein the sending made-up data comprises: 
 (a) when the destination FIU detects a slowdown in the arrival of data over the network, sending filled lines to the destination FTE, and  
 (b) when the destination FIU detects unexpected delays in the arrival of data, sending stalling lines to the destination FTE.  
 
     
     
         29 . A method as in any of claims  2 - 28  wherein the originating and the destination facsimile terminal equipment operates according to the G3 protocol.  
     
     
         30 . A method as in any of claims  2 - 28  wherein the network is of unknown and unpredictable delay.  
     
     
         31 . In a system wherein an originating facsimile terminal equipment (FTE) connects to an intermediate digital network via an originating facsimile interface unit (FIU) and wherein a destination FTE connects to the network via a destination FIU, the destination FIU comprising: 
 (a) means for receiving data from an originating FTE via the network; and    (b) means for, while the destination FIU is waiting for data from the originating FTE, sending a made-up data to the destination FTE to prevent protocol timeouts of the destination FTE.    
     
     
         32 . In a system wherein an originating facsimile terminal equipment (FTE) connects to an intermediate digital network via an originating facsimile interface unit (FIU) and wherein a destination FTE connects to the network via a destination FIU, a FIU programmed to perform: 
 while the FIU is waiting for data from an originating FTE, the FIU sending a made-up data to a destination FTE to prevent protocol timeouts of the destination FTE.    
     
     
         33 . An FIU as in    claim 32    wherein the data being sent by the originating FTE is scan-line data of a document being sent, and wherein the made-up data comprises data which has a valid format and which was not part of the original document.  
     
     
         34 . An FIU as in    claim 33    wherein the FIU is programmed to send the made-up data to the destination FTE when the destination FIU has not received a scan line from the originating FIU, and wherein the made-up data comprises a valid scan line.  
     
     
         35 . An FIU as in    claim 34    wherein the destination FIU sends made-up data to the destination FTE until the FIU has accumulated some data from the originating FTE.  
     
     
         36 . An FIU as in    claim 35    wherein the FIU is further programmed to send made-up data to the destination FTE until the destination FIU receives an all-white scan line, the method further comprising, when the destination FIU receives an all-white scan line, sending to the destination FTE additional white scan lines.  
     
     
         37 . An FIU as in    claim 32    wherein the FIU is programmed to send the made-up data to the destination FTE when the FIU has received at least some of a scan line from the originating FIU, and wherein the made-up data comprises some of the received scan line and additional data.  
     
     
         38 . An FIU as in    claim 32    wherein the kind of made-up data sent to the destination FTE depends on the number of complete, unprinted scan lines that have been received by the FIU over the network.  
     
     
         39 . An FIU as in    claim 38    wherein the sending made-up data comprises: 
 (a) when the destination FIU detects a slowdown in the arrival of data over the network, sending filled lines to the destination FTE, and  
 (b) when the destination FIU detects unexpected delays in the arrival of data, sending stalling lines to the destination FTE.  
 
     
     
         40 . An FIU as in any one of claims  32 - 39  wherein the originating and the destination facsimile terminal equipment operates according to the G3 protocol.  
     
     
         41 . An FIU as in any one of claims  32 - 39  wherein the network is of unknown and unpredictable delay.  
     
     
         42 . In a system wherein an originating facsimile terminal equipment (FTE) connects to an intermediate digital network of unknown and unpredictable delay via an originating facsimile interface unit (FIU) and wherein a destination FTE connects to the network via a destination FIU, wherein the originating and the destination facsimile terminal equipment operates according to the G3 protocol, a memory medium comprising software programmed to provide facsimile communications by: 
 (a) the originating FTE sending data to the destination FTE via the originating FIU and the destination FIU;    (b) the originating FIU sending the data to the destination FIU;    (c) while the destination FIU is waiting for data from the originating FTE, the destination FIU sending a made-up data to the destination FTE to prevent protocol timeouts of the destination FTE;    (d) the originating FTE, at the end of sending a page of data, sending an end-of-page signal to the destination FTE via the originating FIU;    (e) the originating FIU delaying acknowledgment to the originating FTE of the end-of-page signal; and    (f) in response to the delayed acknowledgment, the originating FTE sending an another end-of-page signal to the destination FTE via the originating FIU, thereby allowing the destination FIU and the destination FTE to complete their end-of-page protocol, and, in an error correcting mode (ECM) in which page data is broken up into frames, 
 (g) packaging into frames all page data sent to be sent to the destination FTE;  
 (h) sending all page data to the destination FTE as the packaged frames;  
 (i) keeping a copy of each packaged frame sent to the destination FTE; and  
 (j) in response to a request from the destination FTE for retransmission of a frame, sending a copy of the requested frame,  
   wherein the data being sent by the originating FTE is scan-line data of a document being sent, and wherein the made-up data comprises data which has a valid format and which was not part of the original document, and    wherein the software is further programmed such that the destination FIU sends the made-up data to the destination FTE when the destination FIU has not received a scan line from the originating FIU, and wherein the made-up data comprises a valid scan line, and    wherein the software is further programmed such that the destination FIU sends made-up data to the destination FTE until the destination FIU has accumulated some data from the originating FTE,    wherein the software is further programmed such that the destination FIU sends made-up data to the destination FTE until the destination FIU receives an all-white scan line, the memory medium further comprising, when the destination FIU receives an all-white scan line, sending to the destination FTE additional white scan lines, and    wherein the kind of made-up data sent to the destination FTE depends on the number of complete, unprinted scan lines that have been received by the destination FIU over the network, and wherein the sending of made-up data comprises: 
 (a) when the destination FIU detects a slowdown in the arrival of data over the network, sending filled lines to the destination FTE, and  
 (b) when the destination FIU detects unexpected delays in the arrival of data, sending stalling lines to the destination FTE.  
   
     
     
         43 . In a system wherein an originating facsimile terminal equipment (FTE) connects to an intermediate digital network via an originating facsimile interface unit (FIU) and wherein a destination FTE connects to the network via a destination FIU, a memory medium comprising software programmed to provide facsimile communications by: 
 (a) the originating FTE sending data to the destination FTE via the originating FIU and the destination FIU;    (b) the originating FIU sending the data to the destination FIU; and    (c) while the destination FIU is waiting for data from the originating FTE, the destination FIU sending a made-up data to the destination FTE to prevent protocol timeouts of the destination FTE.    
     
     
         44 . A memory medium as in    claim 43    wherein the data being sent by the originating FTE is scan-line data of a document being sent, and wherein the made-up data comprises data which has a valid format and which was not part of the original document.  
     
     
         45 . A memory medium as in    claim 44    wherein the software is further programmed such that the destination FIU sends the made-up data to the destination FTE when the destination FIU has not received a scan line from the originating FIU, and wherein the made-up data comprises a valid scan line.  
     
     
         46 . A memory medium as in    claim 45    wherein the software is further programmed such that the destination FIU sends made-up data to the destination FTE until the destination FIU has accumulated some data from the originating FTE.  
     
     
         47 . A memory medium as in    claim 45    wherein the software is further programmed such that the destination FIU sends made-up data to the destination FTE until the destination FIU receives an all-white scan line, the memory medium further comprising, when the destination FIU receives an all-white scan line, sending to the destination FTE additional white scan lines.  
     
     
         48 . A memory medium as in    claim 43    wherein the software is further programmed such that the destination FIU sends the made-up data to the destination FTE when the destination FIU has received at least some of a scan line from the originating FIU, and wherein the made-up data comprises some of the received scan line and additional data.  
     
     
         49 . A memory medium as in    claim 44    wherein the kind of made-up data sent to the destination FTE depends on the number of complete, unprinted scan lines that have been received by the destination FIU over the network.  
     
     
         50 . A memory medium as in    claim 49    wherein the sending of made-up data comprises: 
 (a) when the destination FIU detects a slowdown in the arrival of data over the network, sending filled lines to the destination FTE, and  
 (b) when the destination FIU detects unexpected delays in the arrival of data, sending stalling lines to the destination FTE.  
 
     
     
         51 . A memory medium as in    claim 43    wherein the software is further programmed to provide facsimile communications by: 
 (d) the originating FTE, at the end of sending a page of data, sending an end-of-page signal to the destination FTE via the originating FIU;  
 (e) the originating FIU delaying acknowledgment to the originating FTE of the end-of-page signal; and  
 (f) in response to the delayed acknowledgment, the originating FTE sending an another end-of-page signal to the destination FTE via the originating FIU, thereby allowing the destination FIU and the destination FTE to complete their end-of-page protocol.  
 
     
     
         52 . A memory medium as in    claim 43    wherein the software is further programmed to provide facsimile communications by, in an error correcting mode (ECM) in which page data is broken up into frames, 
 (d) packaging into frames all page data sent to be sent to the destination FTE;  
 (e) sending all page data to the destination FTE as the packaged frames;  
 (f) keeping a copy of each packaged frame sent to the destination FTE; and  
 (e) in response to a request from the destination FTE for retransmission of a frame, sending a copy of the requested frame.  
 
     
     
         53 . A memory medium as in    claim 52    wherein the destination FIU keeps a copy of each packaged frame sent to the destination FTE until the frame is acknowledged by the destination FTE.  
     
     
         54 . A memory medium as in one of    claims 43    to    53    wherein the originating and the destination facsimile terminal equipment operates according to the G3 protocol.  
     
     
         55 . A memory medium as in one of    claims 43    to    53    wherein the network is of unknown and unpredictable delay.