With all the noise about replacing traditional PSTN voice systems with VoIP, faxing doesn’t seem to get much attention. Yet just as VoIP frees you from unnecessary phone bills. Replacing old fax machines with new ones can save you money in many ways. In this article, we look at how new protocols and devices replace the old infrastructure.
The old fax system uses a standard called T.30. Which was formally adopted in the 1980s and has taken hold around the world. Most fax machines you know use the T.30 protocol, and two fax machines using the same protocol can communicate with each other without a problem. But what happens if your company switches to VoIP and stops using telephony? We all know that fax machines have their own phone numbers and depend on the PSTN system to work – can fax machines to be migrated as well?
Unfortunately, VoIP technology is focused on voice data transmission. This means that some of the optimizations used by VoIP systems for sound are totally unsuitable for the transmission of data such as images. The result is very unsatisfactory. A new protocol was therefore needed to tell encoders and intermediaries that the data being transmitted was not web or voice data, but something else: the T.38 protocol was published in 1998.
It should be noted that T.38 does not work alone. A protocol is always needed to establish and set up the call in the first place. Today, that protocol is usually SIP – a good example of why SIP is so popular. It simply does what it can and leaves the rest to other protocols.
Fax over IP also uses UDP instead of TCP, because of the confirmation and retransmission procedures. Required by TCP can cause delays or even cancellation of faxes. To compensate for the problems caused by the lack of these methods, the T.38 protocol sends redundant data so that the fax can be recovered if the receiving system did not receive the previous packets.
To use Fax over IP on a network, you must have a T.38-compatible fax machine. Of course, only if you actually have a piece of paper that needs to be sent immediately to someone who, for whatever reason, can’t scan it and get a copy – based on a T.38 facsimile, an individual user can simply configure a computer to fax the image.
And that’s the beauty of IP. There are so many diverse approaches to accomplishing the same goal.
Cecilia Lyman Robertson is a 44-year-old CEO who enjoys networking, VoIP phone, and Fax Sending Service. She has a post-graduate degree in business studies.