Can DSL Save You Money?

The Trends section of last quarter's newsletter mentioned new high speed ways to access the Internet were right around the corner. To everyone's surprise, DSL has taken off like a rocket in the past few months. Well on its way to becoming widely available in the greater Chicago area, DSL is poised to eclipse cable modems as the next primary method of accessing the Internet. It now appears that DSL will provide faster access at a lower cost for a business than almost any other dial-up method, including a regular modem connection. And it provides the fastest Internet access for home use, aside from cable modems, at approximately the same monthly cost as a second phone line.

What Is DSL?

DSL is a relatively new technology based on existing phone connection technology such as ISDN. DSL is an acronym that stands for Digital Subscriber Line. It uses standard copper phone wires, but does not take over a phone line like a modem.

This means you can still make phone calls, even while connected to the Internet! By separating voice and data into discrete channels, the data portion can use new, optimized switched connections, rather than the older "legacy" phone network designed decades ago. This allows DSL to achieve significantly faster speeds than existing dial-up connections using modems or ISDN.

DSL speeds range from 144 kbps to 1.56 Mbps. By contrast, a modem dial-up connection will normally achieve around 44 kbps, and an ISDN connection can achieve 128 kbps. So you can see how DSL can be many times faster than your existing dial-up connection.

How Can I Save Money?

The key is that DSL has no usage charges, despite being connected 100 percent of the time. On business phone lines, Ameritech charges a per-minute rate for voice and data calls. ITS analyzed typical usage charges for hypothetical business customers using modem and ISDN dial-up connections. The bottom line: if your company spends more than about two hours per day online, DSL service is the same or cheaper for a higher speed connection. You may also see savings in labor costs due to potential time savings from the higher speeds.

Business DSL service allows anyone on the network to have high speed Internet access. You no longer need to have multiple phone lines dedicated to modem use, or go through the hassle of sharing one line among several users. Business service also comes with several e-mail boxes, allowing all employees to have an e-mail address.

Types of DSL

At least five varieties of DSL exist, but there are three main types you are likely to encounter. ADSL, or Asymmetrical DSL, was originally designed for video-on-demand applications. ADSL is faster in the downstream than the upstream direction, so its asymetrical approach is perfect for surfing the web, where users continually download text and graphics.

SDSL, which stands for Symmetrical DSL, provides high bandwith in both directions. This is ideal for sending large files or hosting a small web site.

IDSL is the third most common type of DSL. Integrated DSL is the slowest of the three DSL options listed here, but still offers a connection speed about four times that of a standard 56k modem. IDSL can work at almost any distance, so may be available to customers even if faster DSL speeds are not.


DSL is not currently available in all physical locations, but availability is improving rapidly. Ameritech sometimes imposes distance limitations on DSL service, so whether you can get service today may depend on your distance from the nearest central office that can provide DSL service. A central office is where Ameritech keeps its phone equipment for a given area. The speeds available at your location also depend on this distance, since the closer you are to the central office the maximum possible speed increases. Most local areas without faster DSL service now appear to be slated for installation within the next six months. For more information on the availability and cost of DSL in your area, please give our technical staff a call, or visit the DSL section of our web site.


The main competitor to DSL is cable modems, also covered in last quarter's newsletter. Cable TV providers plan to offer high speed Internet service over their cable networks. While cable modems promise a high speed connection, they have several downsides. The connection bandwidth is shared among many users, usually an entire neighborhood. As traffic increases, your speeds decrease. @Home, the largest cable ISP, recently began severely limiting bandwidth on uploads, decreasing the attractiveness of cable modems for web servers.

By comparison, DSL does not require that new cable be installed, as is the case with most local cable service, so DSL service is becoming available to more customers every day.

August 1999

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