Telecommunications from A to Z

Pots -- Plain Old Telephone Service -- is the standard telecommunications tool most of us have in our homes. It is ubiquitous, reasonably priced (usually) and reliable.

Modern 56-kilobit-per-second (that's 56,000 bits-per-second, called 56 kbps) modems are asymmetrical, receiving data at speeds up to 53,000 bits-per-second (bps) and transmitting at up to 33,600 bps (we're not 100 percent certain what happens to the other 3000 bits each second).

Like the car ad says, though, your mileage may vary. Most modems sold in the last few years were 28.8 kbps modems (sending and receiving at up to 28,800 bps) or 33.6 kbps modems.

ISDN, or Integrated Services Digital Network, was the first high-speed connection available to consumers. However, at 56,000 or 128,000 bits per second, it is at most about four times faster than current modems.

ISDN can get quite pricey, too, with a combination of flat fees and per-minute charges. ISDN rates have started coming down as telephone companies prepare for DSL and try to keep customers from switching to cable modems.

Unlike ISDN, cable modem service is always on and far faster, at 760,000 to one million bits per second -- and up. Unlike the services offered by the telcos, cable companies are set up much like an office local area network. Under this setup, the huge pipeline running through a neighborhood is shared among all the users.

The price to install ISDN and cable modem service is comparable, about $150. ISDN usually requires a visit from a specially trained phone company technician, and existing modems do not work on ISDN lines (the ISDN devices -- called terminal adapters -- cost $200 to $1000). Cable Internet access also requires a visit from a technician and, like ISDN, requires a special adapter in place of an existing modem.

The brand new kid on the block is xDSL, or Digital Subscriber Line. DSL comes in several flavors, with the current favorite being Adsl. The A stands for asymmetrical, with downstream speeds being higher than upstream speeds. The Adsl standard pushed by U.S. computer and telephone companies received international approval in late October.

DSL is limited to about 1.6 million bps for now, but that may increase. Prices are higher than cable modems, but unlike cable it is a point-to-point connection.

VPN, or Virtual Private Networking, takes an Internet connection and sets up an encrypted route between the PC and the destination computer. This allows firms to send sensitive information over the public Internet, all for the price of a local phone call to the local Internet service provider.

-- S.E.B.

See also New connectivity tools bring outback staff closer to home.

From THE COLE PAPERS, November 1998, Copyright © 1998, All Rights Reserved.