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Faxing over VoIP

VoIP Faxing;  Faxing over VoIP can be a challenge, but with a few configuration changes on your current fax machine, you may find fairly reliable faxing over your VoIP Internet connection. 

Faxing over a VoIP connection.

Information on Alarms and Credit Card machines over VoIP

First some background on faxing and VoIP.

Faxing has been around for years and most of the protocols were written with the intent of sending those signals over traditional phone circuits using sounds.  Those sounds were turned back into data by the receiving fax machine, which expects a constant, steady transmission of data, without any loss.  If there is some loss of data the receiving fax machine will shut down the transmission. 

The problem is that the codecs used by VoIP IADs are designed to compress voice, not the analog signals sent and received by modems.

In a VoIP Internet world, voice is first converted into packets and then they are sent over the connections that make up our our vast Internet.  They may take slightly different times to arrive at their destination.  In doing so some packets may be discarded, but the end result is that the receiving VoIP device has enough packets to make a clear and understandable conversation. 

We suggest these settings on a fax machine for faxing over VoIP; slowing the transmission rate down and allowing the machine to continue receiving the transmission even though a few bits of data were lost, then faxing over VoIP can become more consistent.  Our suggestions in many cases can resolve issues that prevent faxing over a VoIP connection, but not in all cases.  If after trying and making all the VoIP fax changes we suggest you still cannot fax over your connection then try a Internet Fax service.

G711 or Non-Compressed Codec

First make sure that your VoIP fax connection (the line that you fax on) is set to G711.  This is a non-compressed codec.  G729 uses compression and will make the fax fail.  Some providers have a "Bandwidth Saver" setting.  This would be a compressed codec.  Make sure this is Not enabled.  If you do not have access to this setting call your provider and make sure your connection is set for G711.

Use the fax machine's navigation make the correct BAUD and ECM settings.You will want to make these changes:

Test faxing by using the HP Test Fax Service:

More on Baud rates & ECM settings:

We have added some additional information about these two important settings and included some instructions on making these adjustments on some fax machines.  voip fax settings

There are some other things that you will want to check, especially if you are still experiencing communication errors.  Some fax machines, especially Brother, have an Overseas Mode, which can be enabled before a VoIP Mechanic will help make your fax machine usable over VoIP.fax. This setting makes temporary changes to the fax tones to accommodate noise and static and should be set before each outgoing fax. Check for the following:

If you having problems connecting and are getting a fast busy signal when faxing, your fax machine is most likely not getting connected. (Try dialing the fax number from a different phone, and first check if you hear rings and then receive the traditional fax tone, as a test.)  If so, then you will want to check the fax connection for the following:

Settings to fax over VoIP for Canon fax machines.

Try these settings to for VoIP for Panasonic fax machines.

When faxing over VoIP with a Brother Fax machine make these settings changes.