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About ECM & Baud Rates

How to Fax over VoIP

Faxing over VoIP successfully;  VoIP Mechanic recognizes that not every fax machine comes with implicit easy to find instructions for slowing down the BAUD rate to 9600.  Adding to this problem is that most recent fax machines transmit at higher speeds than 9600, so we have started to list some fax model's instructions to lower the transmission speed to a baud rate of 9600, which will help you have better success when faxing over a VoIP Internet line connection.  We recognize that these instructions can be excluded from many of the manufacturers' manuals and are also difficult to locate from any source, even when calling your fax manufacturer's support personnel.  So to try to alleviate some of the frustration in achieving this important setting, we have decided to try to list some instructions to lower the baud rate for some fax models.

For users who can access the Advance View Settings on their ATA device, we have included some settings that will help faxing.  These settings should be done along with the adjustments that you make on the fax machine itself.  ATA settings for faxing over VoIP.

Help with VoIP faxing.Why you need to lower the baud rate to 9600.

Faxing over VoIP can present certain challenges which require a slower transmission speed, so that most of the data get to it's destination. Packet loss, jitter, and latency all add up to corrupt a fax transmission over VoIP.  When a fax machine determines that data is lost, it will shut down the transmission, even though with some bits of data lost you would still have a workable document.  By slowing down the transmission speed to 9600, you increase the probability that most of the data will make the trip.  Use VoIP Mechanic's How to Lower the baud rate on some fax machines.

Why you need to disable ECM (Error Correction Mode).

The second setting that can also be critical for faxing over VoIP is turning off ECM (error correction mode).  Most newer fax machines have ECM capability, which analyzes the received frames and detects any corrupted data.  Noise, poor signal strength or packet loss can cause part of the the fax information to be lost during transmission.  If any is detected, then a retransmit signal is sent until a error free frame is received.   The problem with this setting over VoIP is that some packet loss, latency or jitter will usually exist on an Internet connection.  The retransmits tend to increase the call duration, adding to the instability of the fax, creating additional  retransmits which then quickly lead to failure with a communication error.  If packet loss on a network gets to a 1 or 2 percent level then faxes will fail consistently.  By disabling ECM, which VoIP Mechanic recommends, the receiving fax machine will not continually request any slightly corrupted transmissions to be resent, ensuring a greater chance of a completed fax.  This could result in a fax image that is of slightly poorer quality (in most cases probably not even noticeable), but in most cases it should be more than sufficient.  Additionally, along with ECM off and a lower Baud Rate -See Baud Rate), a normal resolution setting, rather than high or an ultra-fine quality resolution the success rate of faxes will significantly increase.

How to Disable ECM on most HP Fax machines:

These settings should work closely for most HP fax machines.  If you do discover any slight differences, you should look to locate the ECM setting in the Advanced Features Setup menu.

For most HP 7000 model Officejets.
  • Press Setup
  • Press the down arrow until you get to Advanced Fax Setup
  • Then hit OK.
  • Press the down arrow until Error Correction Mode displays. 
  • Then hit OK.
  • Press the right arrow until OFF displays.  Then hit OK.

For most HP 2000, 4100, 5000, 6000 & 6100 model Officejets.

  • From the Front Panel Press Menu.
  • Hit the Right Arrow until you get Advanced Fax Setup.  Then hit Enter.
  • Hit the Right Arrow until you get Error Correction Mode.  Then hit Enter.
  • Hit the Right Arrow for Error Correction Mode Off.  Hit Enter.

How to Disable ECM HP Officejet 7300/7400 series all-in-one

  • Press Setup.
  • Press 5, and then press 6.  (This will display the Advanced Fax Setup Menu and then selects Error Correction Mode.)
  • Press the Down Arrow to enable the Off (or ON) Option.
  • Press OK.

** Pease Note:  Turning off ECM on these models by completing the above settings only applies to outbound faxes.  If the speed of the Fax is not adjusted to Slow or Medium and the fax is left at the default fast speed, it will automatically send the fax with ECM on regardless of the above settings.

How to Disable ECM on some Canon Fax machines.

For Canon models B115, B120 & B140 fax machines.

  • Press Function.
  • Press Start/Copy.
  • Hit the Right Arrow until TX Settings appears.  Press Start/Copy.
  • Hit the Right Arrow until ECM TX appears.
  • Hit Start/Copy to turn it OFF.
  • Note: By hitting Function at any time will return you to the previous level.

For Canon Fax Phone B95.

  • Press Function.
  • Press Start/Copy.
  • Hit the Right Arrow until TX Settings appears.  Press Start/Copy.
  • Hit the Right Arrow until ECM TX appears.
  • Hit Start/Copy to turn it OFF.
  • Hit Function to return you previous level until you can choose ECM RX by hitting the Right ArrowPress Start/Copy to turn it OFF.

How to Disable ECM on UX CL220, UX A255, & UX A260 Sharp Fax machines.

  • Hit the Function Arrow UP Twice
  • Next hit the Right Arrow Once.  This will bring you to Option Setting.
  • Use the Down Arrow 6 times for ECM Mode.
  • Press 2 to Disable ECM.
  • Press Stop.

Note: These Sharp fax models (UX CL220, UX A255 and the UX A260 are set to transmit and receive with a 14,400 Baud setting.  If the other machine is slower, they will automatically adjust downward.  There is not a setting that we are aware of to lower the default Baud rate to 9600.  Some users do say that they have used a fax over a VoIP line at 14,400, so by disabling ECM it could work.  You may also want to set the resolution to Standard.


How to lower Baud rates on some fax machines.