Analog vs ISDN vs DSL: Which Connection Is Right for You?

by Brian McConnell

Until recently, businesses had two choices when connecting to the internet. They could pay about $20 per month for a slow, often busy, dialup (modem) connection to the internet. Or, they could pay about $2,000 per month for a fast, dedicated connection called a T1 line. In the past two years, several new alternatives have become available, and will become commonplace over the next few years. This article will help you pick the right internet connection and save money when you shop for services for your business.

Currently available internet connections fall into the following general categories: POTS (plain old telephone service), ISDN (integrated services digital network), T1/Frame Relay, DSL (digital subscriber line), cable modem, and wireless internet service. Each type of connection has its stengths and weaknesses. Typically, only one or two of these options will be available in a given neighborhood (availability is one of the big issues; more on that later).

POTS—Plain Old Telephone Service

By far, the most common type of internet connection is the dialup modem connection. New high speed modems deliver speeds of up to 56 Kbps (56,000 bits of information per second). While this might sound fast, 56 Kbps is not fast enough for videoconferencing, multimedia applications, large file transfers, etc. While this is fine for the casual user, businesses will typically want higher speed connectivity.

PRO: Cheap and universally available
CON: Slowest type of connection available

ISDN—Integrated Services Digital Network

ISDN has been available in some parts of the country for nearly a decade. Envisioned as the "POTS line for the next century," ISDN is now used to deliver higher internet connection speeds than analog modems. ISDN delivers connection speeds up to 128 Kbps, about 4 times faster than a typical modem and is also used for videoconferencing workstations.

ISDN, unlike DSL and cable modems, is available in most metropolitan areas, although there are still many cities where it’s not available. There are also many ISDN modems and routers on the market, so hardware is cheap and plentiful.


Read "ISDN: How to Get a High Speed Connection to the Internet"

The main problem with ISDN: the telephone companies overprice it (you have to pay per minute of use), and it's not dramatically faster than analog modem connections. In many cases, you barely notice the improvement over a good 56 K modem.

PRO: Faster than analog modems, widely available in most metro areas
CON: Telcos overcharge for use, not dramatically faster than analog service

T1/Frame Relay Service

T1/Frame Relay are commonly used to connect offices to the internet. Rather than ordering dialup service for each user, a company will buy a high speed connection which is shared by the entire office. T1/Frame Relay deliver speeds up to 1.5 Mbps (1.5 million bits of information per second), about 30 times faster than the best analog modem connection, and about 12 times faster than an ISDN connection.

T1/Frame Relay are available from almost every telephone exchange, so availability is not usually an issue. The problem is cost. T1/Frame Relay service is not cheap. A typical T1 internet connection costs about $2,000 per month, or nearly $25,000 per year.

PRO: Much faster than dialup service, widely available
CON: Expensive

DSL—Digital Subscriber Line

DSL (digital subscriber line) is a revolutionary new service which delivers high data speeds at much lower prices than T1 or Frame Relay service. DSL lines operate at different speeds, depending on the configuration, and on your distance from the telephone company central office. Speeds typically range from around 384 Kbps to 1.5 Mbps (T1 speed). Some versions of DSL can deliver speeds up to around 6 Mbps (6 million bits per second). There are many different flavors of DSL service. The most popular types are SDSL (symmetric DSL) and ADSL (asymmetric DSL).

SDSL typically delivers up to T1 (1.5 Mbps) speeds in both directions (from the internet to you, and from you to the internet). SDSL is essentially a cheaper replacement for a T1 line. This is a popular class of service for businesses that are hosting web sites and other applications on their networks. Service typically prices out cheaper than T1 service, often under $1,000 per month. Most vendors offer slower speed service with prices starting around $200 per month. Maximum speeds available to you will depend on your distance from the telephone company's central office.

ADSL delivers more information downstream (from the internet to you) than upstream (from you to the internet). Most small businesses and individual users spend most of their time retrieving information from the internet (i.e., browsing web pages, downloading files, playing a sound clip, etc.). This asymmetric approach allows the same circuit to carry data more efficiently. Since a large block of upstream bandwidth would be wasted, it is used instead to send data downstream. ADSL delivers downstream speeds ranging from 128 Kbps to several megabits (as high as 6 Mbps), and delivers upstream speeds ranging from 64 Kbps to 1.5 Mbps. This varies by configuration, and your distance from the telephone company's central office. Pricing ranges from as low as $50 per month for relatively slow speeds, to several hundred dollars per month for 1.5 Mbps or faster service. It is dramatically less expensive than T1 or Frame Relay service, and usually just as fast.

The main issues with DSL are availability and compatibility. DSL is being widely deployed only within major metropolitan areas. Rural areas are unlikely to have DSL in the near future. Furthermore, since DSL has proven to be popular, there can sometimes be considerable delay having DSL installed. The other big problem is compatibility. There are many flavors of DSL. There is work underway to create a universal standard for DSL. However, it will be a while before the standard is widely supported.


Read "DSL and ADSL"

PRO: High speed service, very affordable, adapts to line conditions
CON: Not widely available, incompatibility between vendors

Cable Modems

Cable modems offer a very inexpensive way to connect your office or home business to the internet. Cable modems operate somewhat differently than conventional modems. Whereas a conventional modem is wired to a dedicated circuit which runs from your location to the phone company, a cable modem uses the cable TV company's system as a shared data network (sort of like an intercom system). All of the devices connected to the network can talk and listen to each other.

Cable TV systems are designed to deliver a lot of information (moving pictures and audio) from the head end (central distribution point) to users (television sets). These networks are capable of carrying large amounts of computer data in the downstream direction. They do not usually carry as much information in the upstream direction.

One problem with cable modems is variability of speed. If many users are using the network simultaneously, your connection speed will decrease. It is basically impossible to precisely predict connection speeds. On average, cable modems deliver between 300 Kbps to 1.5 Mbps. Many vendors are instituting usage policies and are managing the bandwidth to better provide a specific speed level to all users.

PRO: Very inexpensive (slightly more than dialup service), continuously connected
CON: Variable quality of service, not widely available to businesses

Wireless Internet Service

If you live in a rural area, or in a downtown metropolitan area, wireless internet service can deliver very high connection speeds without using conventional phone lines. This is a particularly useful way to "wire" an office building in a downtown location. Speeds vary widely, from 1.5 Mbps to very high speeds (i.e., 45 Mbps). The connection speed varies depending on the carrier, technology used, and your distance from a receiving station.

This technology is still underutilized and hard to find. There are now major players in this market that promise to increase availability over the next few years. While not necessarily a first choice at this time, in the future, wireless high speed service will rival all the other forms of wired high speed service.

PRO: Very high speeds, independent of land-based telephone networks, cost effective
CON: Only available in very specific regions

What Connection Is Best for Me?

The answer really depends on what is available in your area, and what you are trying to do. This article assumes that you are a small to mid-sized business that plans light to moderate internet use (i.e., you are not hosting a high traffic web site). If DSL service is available in your area, this is probably your best choice in terms of performance and cost. The next best thing is cable modem service, with the caveats about unpredictable, variable performance. If neither cable nor DSL service is available, and you require a high speed (>128 K) connection, then you're probably stuck with T1/Frame Relay service, although wireless may also be an option. If you don't require high speed connectivity, then a shared ISDN connection will provide decent performance at a reasonable price.

Helpful Resources

Hello Direct has partnered with InternetConnect to offer DSL and other data services to customers. InternetConnect has a web search engine that enables you to search for pricing and availability for high capacity voice and data service in your neighborhood.

If you have any more questions regarding high speed internet access or any other telecommunications technology-related question, hop on over to my "Ask Brian" page and post a question there.