Method and apparatus for improving performance of facsimile transmissions over IP networks

• US 6,563,599 B1
• Filed: 10/04/1999
• Issued: 05/13/2003
• Est. Priority Date: 10/04/1999
• Status: Expired due to Term

• Current Assignee: MACOM Technology Solutions Holdings, Inc.
• Original Assignee: Conexant Systems Incorporated (Synaptics Incorporated)
• Inventors: Whitfield, Michael
• Primary Examiner(s): Nguyen, Madeleine
• Application Number:
  US09/411,508
• Time in Patent Office: 1,317 Days
• Field of Search: 358/1.15, 358/442, 358/434, 358/440, 358/400, 358/402, 358/426.01, 358/426.02, 379/100.01, 714/39, 714/41, 714/47, 714/748, 714/736, 714/749, 714/822, 709/311, 709/310, 713/153
• US Class Current: 358/1.15
• CPC Class Codes: H04N 1/00209 Transmitting or receiving image data, e.g. facsimile data, via a computer, e.g. using e-mail, a computer network, the internet, I-fax
• CPC Class Codes: H04N 1/32641 of transmission or transmitted data, e.g. interruption or wrong number of pages
• CPC Class Codes: H04N 1/32795 Arrangements for keeping the communication line open
• CPC Class Codes: H04N 2201/0015 Control of image communication with the connected apparatus, e.g. signalling capability
• CPC Class Codes: H04N 2201/0093 Facsimile machine H04N2201/0094 takes precedence

Abstract

A method for avoiding time-outs during facsimile transmissions over IP networks is disclosed. In the disclosed method, T.30 commands and responses are passed in V.21 channel 2 (“ch2”) modulation with HDLC framing. Normally, when a T.30 message is sent, the V.21 ch2 carrier starts, then there is one second of HDLC flags, followed by the contents of the message. In a method according to the present invention, the V.21 ch2 carrier and HDLC flags are started when a response is late from the remote facsimile machine. This step is preferably initiated on occasions when a time-out would otherwise be likely in view of the late response. If the response from the remote facsimile machine arrives during the one second HDLC flags, the message is sent to the remote facsimile normally. If the message has not been received by the end of the one second HDLC flags, this period is extended for an additional two seconds. If the response arrives during this extended period of HDLC flags, the message is sent immediately. This HDLC flags preamble extension method avoids time-outs by making the facsimile machine think the message is being received, rather than doing a time consuming restart.

If the message has not been received by the end of the extended three second period of HDLC flags, then the preferred method may fall back on an alternative spoofing scheme.

Claims

1. A method for use by a gateway device for sending facsimile transmissions over an internet protocol network, comprising the steps of:

determining whether a response has been received from a remote facsimile machine before a time-out has occurred in accordance with a predetermined protocol;

if said response has not been received, starting an HDLC encoder to send HDLC flags for a predetermined period of time, before said time-out occurs, as preamble HDLC flags for said response;

determining whether said response has been received from the remote facsimile machine before expiration of said predetermined period of time; and

if said response is received within said predetermined period of time, sending said response to a local facsimile machine;

otherwise, sending a command repeat message to said local facsimile machine.

2. The method according to claim 1, wherein:

the predetermined period of time is three seconds.

3. A facsimile over network method for use by a gateway device, said method comprising:

starting a first time-out period;

waiting for a response from a remote facsimile device for delivering said response to a local facsimile device;

monitoring said first time-out period, wherein said first time-out period is shorter than a second time-out period started by said local facsimile device;

transmitting HDLC flags to said local facsimile device upon expiration of said first time-out period for a predetermined flag transmission period;

sending said response to said local facsimile device if said response is received prior to expiration of said predetermined flag transmission period; and

sending a command repeat message to said local facsimile device if said response is not received prior to expiration of said predetermined flag transmission period.

4. The method of claim 3 further comprising:

receiving a command from said local facsimile device in response to said command repeat message.

5. The method of claim 4, wherein said command is not sent to said remote facsimile device.

6. The method of claim 5, wherein if said response is not received prior to expiration of said predetermined transmission period, said predetermined transmission period is extended.

7. The method of claim 6, wherein if said response is not received prior to expiration of said extended predetermined transmission period, sending said command repeat message to said local facsimile device.

8. A gateway device capable of supporting facsimile over network, said gateway device comprising:

a timer; and

a processor capable of starting said timer for a first time-out period, waiting for a response from a remote facsimile device for delivering said response to a local facsimile device, monitoring said timer, wherein said first time-out period is shorter than a second time-out period started by said local facsimile device, transmitting HDLC flags to said local facsimile device upon expiration of said first time-out period for a predetermined flag transmission period, sending said response to said local facsimile device if said response is received prior to expiration of said predetermined flag transmission period, and sending a command repeat message to said local facsimile device if said response is not received prior to expiration of said predetermined flag transmission period.

9. The device of claim 8, wherein said processor is further capable of receiving a command from said local facsimile device in response to said command repeat message.

10. The device of claim 9, wherein said processor does not send said command to said remote facsimile device.

11. The device of claim 10, wherein if said processor does not receive said response prior to expiration of said predetermined transmission period, said processor extends said predetermined transmission period.

12. The device of claim 11, wherein if said processor does not receive said response prior to expiration of said extended predetermined transmission period, said processor sends said command repeat message to said local facsimile device.