One of the most important words in telecommunications is virtual. It is used in a variety of ways, but in reality, it only has one meaning. If you see the word virtual associated with a technology or product, you should immediately say to yourself, It s a lie.

A 56 Kbps modem is a good example of a virtual technology. These devices have attracted a great deal of interest since they were introduced a few years ago. Under certain circumstances, they do offer higher access speeds designed to satisfy the increasing demands of bandwidth-hungry applications and increasingly graphics-oriented web pages. The problem they present is that they do not really provide true 56K access, even under the best of circumstances.

56K modems provide asymmetric bandwidth, with 56 Kbps delivered downstream toward the customer (sometimes) and significantly less bandwidth (33.6 Kbps) in the upstream direction. Although this may seem odd, it makes sense given the requirements of most applications today that require modem access. A web session, for example, requires very little bandwidth in the upstream direction to request that a page be downloaded. The page itself, however, may require significantly more because it may be replete with text, graphics, Java applets, and even small video clips. Because the majority of modem access today is for Internet surfing, asymmetric access is adequate for most users.

The limitations of 56K modems stem from a number of factors. One of them is the fact that under current FCC regulations (specifically Part...