Some customers may experience issues with faxing through their VoIP service. This document is designed to aid in repairing these issues.
THE PROBLEM
The codecs used by VoIP Terminals are designed to compress voice, not the analog signals sent and received by modems and fax machines.
Voice is first converted into packets and then they are sent over the customer’s internet connection. Due to the complexity of the internet and global networks they may take slightly different times to arrive at their destination. In doing so some packets may be discarded, and the end result is that the receiving device may not have enough packets to make a clear and understandable conversation; this causes small amounts of data loss which can cause a fax machine to terminate its task.
By making a few setting changes on the fax machine; slowing the transmission rate down, and allowing the machine to continue receiving the transmission, even though a few bits of data were lost, faxing over VoIP can become more consistent.
THE BASICS
Here are a few things that should be checked first
1. Use a direct connection from the ATA to the fax machine. Try removing any splitters and other devices in that line. Some devices may interfere with the fax transmission, such as, answering machines and caller ID devices
2. Try enabling Overseas Mode (available on certain fax machines)
3. Change the resolution setting to Standard, rather than super fine. This limits the amount of packets that need to be transmitted
4. Try plugging in the power adapter directly into a wall socket, rather than a power strip or surge protector
5. Try placing a DSL filter in reverse position between the ATA and the fax machine
ECM (ERROR CORRECTION MODE)
Most newer fax machines have ECM capability, which analyzes the received frames and detects any corrupt data. Noise, poor signal strength or packet loss can cause part of the fax information to be lost during transmission. If any is detected, then a retransmit signal is sent until an 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. When packet loss gets to a 1 or 2 percent level then faxes will fail consistently. By disabling ECM, 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, but in most cases it should be more than sufficient.
See Appendix A for instructions on how to disable ECM on some common fax machines or consult the user manual.
BAUD RATE
Faxing over VoIP can present certain challenges which require a slower transmission speed, so that most of the data get to its 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 or lower, you increase the probability that most of the data will make the trip.
See Appendix B for instructions on how to lower Baud Rate on some common fax machines or consult the user manual.
APPENDIX A – HOW TO DISABLE ECM ON COMMON FAX MACHINES
Hewlett Packard (HP)
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.
1. Press Setup
2. Press the down arrow until you get to Advanced Fax Setup
3. Then press OK
4. Press the down arrow until Error Correction Mode displays
5. Then press OK
6. Press the right arrow until OFF displays. Then press OK
For most HP 2000, 4100, 5000, 6000 & 6100 model OfficeJets.
1. From the Front Panel Press Menu
2. Press the Right Arrow until you get Advanced Fax Setup. Then press Enter
3. Press the Right Arrow until you get Error Correction Mode. Then press Enter
4. Press the Right Arrow for Error Correction Mode Off. Press Enter
Canon
For Canon models B115, B120 & B140 fax machines.
1. Press Function
2. Press Start/Copy
3. Press the Right Arrow until TX Settings appears. Press Start/Copy
4. Press the Right Arrow until ECM TX appears
5. Press 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.
1. Press Function
2. Press Start/Copy
3. Press the Right Arrow until TX Settings appears. Press Start/Copy
4. Press the Right Arrow until ECM TX appears
5. Press Start/Copy to turn it OFF
6. Press Function to return you previous level until you can choose ECM RX by pressing the Right Arrow
7. Press Start/Copy to turn it OFF
APPENDIX B – HOW TO LOWER BAUD RATE ON COMMON FAX MACHINES
HP6110
1. Press the * and # keys at the same time
2. Press 1, then 2, then 3. (Release each key before pressing the next)
3. Select System Configuration, the select R/W parameters and press Enter
4. Press 153 and then Enter. (This parameter is for sending. The parameter for receiving is 159)
5. Press 2, then Enter. The value should display. (This is the parameter for 9600, 3 is 7200 the lowest baud)
6. Next press Cancel repeatedly until you exit the service menu.
HP4110
1. Press the * and # keys at the same time
2. Press 1, then 2, then 3. (Release each key before pressing the next)
3. Service should now display, press the right arrow button until R/W parameters appears. Then press Enter
4. You should see parameter 0. Press 2, then Enter (This is the parameter for 9600, 3 is 7200 the lowest baud)
5. Next press Cancel repeatedly until you exit the service menu.
HP6100xi, HP7410xi and HP PSC2210
1. Press the * and # keys at the same time
2. Press 1, then 2, then 3. (Release each key before pressing the next.)
3. The display should show Service, press the right arrow button once and System Configuration should display. Press Enter
4. Press the right arrow button until R/W parameters appears. Then press Enter
5. You should see parameter 0. Press 153, then Enter. (Parameter 153 is for sending. The parameter for receiving is 159.)
6. Press 2, then Enter (This is the parameter for 9600, 3 is 7200 the lowest baud)
7. Next press Cancel repeatedly until you see the date and time display.
Canon Fax Phone B95
1. Press Function
2. Press Start/Copy
3. Hit the Right Arrow until System Settings appears. Press Start/Copy
4. Hit the Right Arrow until TX Start Speed appears
5. Choose 9600bps or lower
6. Hit Function to return you previous level until you can choose RX Start Speed by hitting the Right Arrow
7. Choose 9600bps or lower
* Note: 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.
Brother fax machines
1. Press the Menu or Menu/Set key. Then Fax, Miscellaneous and Compatibility
2. Press the Up or Down key until you can select Basic. Basic reduces the modem speed to 9600 bps
3. Press OK or Menu/Set or Set key
4. 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.
