If VoIP aims to completely replace the traditional PSTN system, it has to perform all of its functions and perhaps add a few of its own. As matters stand today, the overwhelming majority of people use the regular telephone network to send and receive faxes. Despite the advances in digital communications, everyone still need a fax machine now and then. There is every reason to believe that no matter how much we come to rely on soft copies for everything, a fax machine will still be needed at some point of time. So IP networks have to suit up and provide the best possible experience if they want to convince users to switch.
There are several problems with letting a fax go over a digital network in the same way that voice does. The difference is that the encoding and compression used by voice algorithms cannot be properly translated over to fax data. If you try and intermingle the two media streams, the fax will come out imperfectly and jumbled beyond acceptance. So we need a separate set of protocols to deal with this kind of information. Traditional PSTN lines use the T.30 protocol for sending and receiving fax messages. The Internet has devised its own known as the T.38 protocol. As usual though the problem lies with intercommunication between the two networks. It would be ideal if we had two Internet fax machines communicating with each other using T.38. In addition to being excellent in quality, this would be free as well.
Unfortunately traditional networks only understand the T.30 protocol. So IP gateways have to perform the conversion in a transparent manner so as to provide interoperation. If you have an account with a hosted SIP provider, contact them and ask them whether or not they provide support for fax over VoIP. Ideally if you use a lot of faxing technology, you should get your own IP compatible T.38 fax machine. But if you don’t want to shell out money to buy a new piece of hardware, you should get a T.38 compatible ATA adapter instead. These will allow you to plug in your own fax machines and will then make them interoperate with digital IP networks.
Many organizations have found that they can do away entirely with faxes. But some customers might still prefer the old ways of sending documents and may not have easy access to an Internet connection. For these situations, it is extremely helpful to have a fax service around to send and receive messages. Make sure that you’re not caught on the wrong foot and plan ahead for your IP fax needs.