How To Send Fax over IP

Using Fax Machine
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There are numerous advantages to sending fax messages over and IP network or the Internet instead of the traditional phone line, and three ways you can send fax over an IP network. The one you choose will depend on your actual situation, facilities, and the nature of your activities. The three options include:

  • Using a fax gateway, through the T.38 protocol;
  • Using the fax-to-email method, through the T.37 protocol; and
  • Sending the fax over a VoIP channel.

One important thing to note about IP Faxing is that fax messages are not sent to and from phone lines as traditionally and hence do not require phone numbers, but are sent to and from IP addresses. Here are three ways to fax over IP.

Using a Fax Gateway Through the T.38 Protocol

This is also called real-time faxing, i.e. the fax messages are sent and received at once, without having to wait and be stored. It works, on the outside, like traditional faxing. Computers can be used to send faxes this way, but more often (as this method is mostly used in corporate environments) IP fax machines are used. What is important is the presence of fax gateways or fax servers that have the necessary mechanisms (including protocol algorithms) to handle faxing, and which make the bridge between the IP network and the PSTN line.

Using the Scan-to-Email T.37 Protocol

T.37 is another protocol that controls fax transmission over IP, but unlike T.38, it works offline, meaning it stores fax messages which are then delivered time after they are sent.

This implies that the fax messages can be saved on servers and retrieved at will, or saved as email attachments.

Using this method, the fax message is scanned producing a TIFF binary image file, which can then be compressed using a standard compressing algorithm like JBIG, for example. The fax is sent to a destination an email address as email attachment.

The receiver of the fax will get the message when he/she checks mail, which might not be immediate. To receive the fax, a standard email client (e.g. Outlook, Thunderbird etc.) can be used, or an Internet fax machine that is designed to work on IP networks and treat with IP Faxing protocols. The Internet fax machine will have the necessary decompression algorithms and standards to have the fax message printed. The email client will send the file to a conventional printer, and the algorithms and fax-handling modules must be present on the computer. This comes with fax software or add-ons.

Sending a Fax Over a VoIP Channel Using the G.711 Protocol

This is maybe the simplest method, which simply involves sending a fax message using a machine connected to a VoIP network (which may be your residential or business VoIP line). This method has encountered many problems, namely with the compression of the fax messages. Finally, it is better if the fax is not compressed, and this is achieved by the G.711 codec. You can have this with fax software available and use it over your VoIP line.

In addition to the methods above, there are services that offer faxing over the Internet with a monthly fee.

They have the necessary servers, software and algorithms; you only pay to get the service. Here is a list of some of those services.