http://www.caprica.com/~dginsberg/isdn.html (World Wide Web Directory, ~04/1995)
ISDN (Integrated Services Digital Network) is a service available through many local phone companies. There are many different service options but the least expensive is the "home user" package. This service provides 2 data grade lines capable of speeds of up to 64K each and allows analog voice on either circuit. So you can login to an online service on one channel and talk to a friend on voice with the other channel.
How Does it Work?
Think of your current telephone service as a garden hose. You have only one stream of water from the facet. You can only use it to do one thing at a time; either water the lawn or wash the car. What if you want to do both at the same time? You can go to the hardware store and get a hose splitter attachment. Now you have split the flow off into two streams. So you can easily wash the car as well as water the lawn at the same time.
ISDN is the same basic theory. It allows you to take a single telephone line and split it to 2 separate services through the magic of digital technology. So instead of being limited to one conversation you can have a voice call and a high speed data call or two voice calls or two high speed data calls all going on at one time!
The basic ISDN telephone company to home user connection is called a Basic Rate Interface(BRI) and it is set up to have two large pipes called Bearer channels (B channels) and one small pipe called a Data channel (D channel). The B channels can be used for either voice or high speed data communication. The D channel contains all of the information the phone company needs to set-up your calls. Some higher end ISDN equipment will even allow you to use part of the D channel for "slow" speed (under 9660 Baud) data sessions.
How do I get On ISDN?
See my ISDN article that will be published in the July Los Angeles Mac UG newsletter. This has more information on ISDN and the info you need to set-up a Mac.
ISDN Consulting Services
If you want to skip some of the confusion of setting up service on your own, I also offer ISDN user consulting at reasonable rates for the Los Angeles area.
Contact me via Email for more information.