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. 


You can set the Baud rate by following these steps:
Press the * and # keys at the same time. Press 1, then 2, then 3. (Release each key before pressing the next.) Select System Configuration, the select R/W parameters and press Enter. Press 153 and then Enter.  (This parameter is for sending.  The parameter for receiving is 159.) Press 2, then Enter.  The value should display. (This is the parameter for V.17 9600.) Next press Cancel repeatedly until you exit the service menu.


You can set the Baud rate by following these steps:
Press the * and # keys at the same time. Press 1, then 2, then 3.  (Release each key before pressing the next.) Service should now display, press the right arrow button until R/W parameters appears.  Then press Enter. You should see parameter 0.  Press 2, then Enter. Next press Cancel repeatedly until you exit the service menu.


You can set the Baud rate by following these steps:
Press the * and # keys at the same time. Press 1, then 2, then 3. (Release each key before pressing the next.) The display should show Service, press the right arrow button once and System Configuration should display.  Press Enter. Press the right arrow button until R/W parameters appears.  Then press Enter. You should see parameter 0. Press 153, then Enter.  (Parameter 153 is for sending.  The parameter for receiving is 159.) Press 2, then Enter. Next press Cancel repeatedly until you see the date and time display.


Press Function. Press Start/Copy. Hit the Right Arrow until System Settings appears.  Press Start/Copy. Hit the Right Arrow until TX Start Speed appears. Choose 9600bps. Hit Function to return you previous level until you can choose RX Start Speed by hitting the Right Arrow. Choose 9600bps.

You may find that these directions will work with other Canon fax machines or be close enough to find the correct TX and RX Start Speeds.


Press the Menu or Menu/Set key.  Then Fax, Miscellaneous and Compatibility. Press the Up or Down key until you can select Basic.  Basic reduces the modem speed to 9600 bps. Press OK or Menu/Set or Set key. Press Stop/Exit.

Note these instructions should work for the following models: Fax-1835C, Fax-1840C, Fax-1940CN, Fax-2440C, Fax-2820, Fax-2825, Fax-2920, MFC-210C, MFC-215C, MFC-240C, MFC-3240C, MFC-3340c, and most other MFC models.