Faxing over IP networks does not work reliably. There are many technical reasons why; I won’t go into them here. This page provides a pretty detailed explanation about why trying to transmit analog modem signals over an IP network will not work — variable jitter, insufficient bandwidth, silence suppression and many other factors in VoIP call handling will work together to destroy your faxes. There are two main solutions in the FoIP (Fax over IP) space:

• T.37 (store-and-forward): Use e-mail as the IP transport medium. T.37 defines a protocol by which faxes are converted to an e-mail message and then delivered to a T.37 endpoint – whether that is someone’s email box, or a device capable of translating the attachment into a fax image and then sending it to the target fax machine using the PSTN.
• T.38 (real-time fax): Use either “Internet-capable” (T.38) fax machines, analog telephone adapters, or a combination of T.38 aware/compatible devices to transmit faxes using special UDP packets.

Neither of these mechanisms is particularly elegant. In fact, the adoption rate of T.38 is quite low among ATA makers, and many implementations are buggy. Also, the fact that T.38 must be implemented on both ends of a call is another nail in the coffin.

Let’s step back a moment here and reconsider what we want to do. Suppose I am a business owner considering (or having switched) to a VoIP network, but I still have my old (non-T.38 capable) fax machine. I want to send faxes to any other fax device in the world, and I don’t care whether the receiver’s equipment is T.38 capable or not. I am willing to invest in a T.38 ATA, and assume that I can do so without too much cost or effort, and that it will work reasonably well. What do I do? Continue reading →

I haven’t had much of a chance to write about technology issues recently; quite frankly, not a lot has been happening that has interested me. Sure, Apple has announced a new MacBook that’s really thin, but, as usual, it has the 100% Apple markup over anything sensible. I mean, $3,000 for a notebook? I know that $1,000 of that is probably to pay for the solid-state drive, but I’m not even convinced that such technology is really necessary. I contrast this to a $500 Acer Eee laptop that would more than meet my needs! (Too bad the name is retarded, kind of like the Nintendo Wii)

Enough about Steve Jobs’ latest money printing scheme; I want to talk about telephony again. I went to a TAUG meeting tonight on the topic of integrating DECT with SIP. DECT is one of those technologies that has been around for a generation but has largely been ignored in North America; only recently has there been any uptake. Most people (myself included, at least up until about 4 hours ago) don’t even know that cordless phone systems that you can buy at Best Buy use DECT – okay, the example I linked to is a bit unfair since it says “DECT 6.0” right in the headline, but you get the idea. My friend Brian had a set of these in 2005 but I wasn’t any the wiser that it wasn’t just a regular WDCT set on the 2.4 GHz spectrum.

Continue reading →