Internet Access Babylon.

• Author: DESMOND, PAUL

HOW CAN COLORADO MANAGERS HANDLE THE BABBLE - T1, ISDN, DSL - OF INTERNET ACCESS OPTIONS?

Your employees are complaining about slow, unreliable or -- gasp -- nonexistent Internet connections. You figure it's time to reassess your access options before a major uprising takes root.

You ask one of your Information Systems staffers what the choices are and hear a stream of acronyms, most only vaguely familiar: T1, DSL, ISDN, POTS, not to mention cable modems. "Can't someone just tell me what I should buy?" you think.

The answer, as is so often the case with technology questions, is, "It depends." It depends on how many users will be gaining access to the Internet, what kinds of files they'll be sending back and forth, how often they need to use the 'Net and what you can afford to spend.

But the decision isn't exactly a formidable one, either, so long as you understand the basics of the various service options. Here we'll discuss the most common ones:

* Dial-up lines (or POTS, for plain old telephone service);

* Integrated Services Digital Network (ISDN), a digital version of dialup lines at more than twice the speed of a POTS line;

* Leased lines, which come in various speeds including T1, which equates to 1.5 million (or M, for megabits) bits per second (bps) -- enough for most small businesses and some not-so-small;

* Digital Subscriber Line, a relatively new service that offers very high-performance connections, if you can get it;

* Cable modems, which are certainly fast, but which come with some performance and security risks that may outweigh that speed.

Dial-up lines are the simplest and cheapest way to get at the Internet. Any number of providers will sell you unlimited Internet access for roughly $20 per month per employee. Potential problems with the service come down to performance and reliability.

Most PCs today come standard with a 56K modem, which will transmit data at around 48,000 bits per second (48 Kbps). These days, that's not so fast, If all you want to do is send simple e-mail messages back and forth, it'll suffice. But if you've got users who frequently use Web pages or send large files, such as those with lots of graphics and photos, they will not likely be happy with the performance of a 56K modem. Similarly, if you've got an office with maybe a half-dozen workers or more, they'd each need their own data line, plus a separate phone line; now your costs are adding up.

On top of that, it's likely that a couple times per day a dialup line will disconnect for no apparent reason, forcing you to dial back in to the network. For most of us, that's frustrating.

The next step up is ISDN. While dialup lines use older, analog technology, ISDN is all digital. Generally speaking, you get improved performance and reliability with digital services. Analog technology requires a conversion between the format used on all computers -- digital -- and that used on most dial-up phone lines, which is analog. This conversion involves plotting each byte at a specific point on an analog wave, depending on what the byte represents. (A byte is series of eight 1s and 0s, or bits, that represent a given character.) If the line is not reasonably clear of interference, things can get fouled up and performance suffers.

It's essentially the same as the difference between an old vinyl record, which is analog, and a compact disk, which is digital. CDs generally sound better, because a simple series of is and Os doesn't get distorted often, as analog waves can.

ISDN, in addition to using digital technology, is also faster. The lowest level of service, called Basic Rate ISDN (BRI), gives you two 64 Kbps channels. One of the 64K channels can be used for regular telephone calls (not coincidentally, it takes a 64 1Kbps digital line to carry a voice conversation), while the other can be used for data. Or you can typically pool the two 64K channels and get a 128K line, a decent speed but not Likely to have your heaviest Web users doing handsprings with joy.

There's also Primary Rate ISDN (PRI), which...