Hayes Microcomputer Products PC Card - Manual (Page 4)

DIVA T/A PC Card Reference Guide 4
What is ISDN?
While you've heard of ISDN, there's a good chance you're unsure
whether you need it - or even what, exactly, it is. Even though ISDN
is globally available, it's so new that understanding it may require a
little investigation.
In simple terms, ISDN is a replacement for plain old telephone
service, which was never designed to meet the needs of the
information age. ISDN uses the same wiring that currently serves
homes and businesses. You get ISDN service from the same
companies who provide telephone service, and you use it to connect
telephones, computers, and fax machines. The difference is that you
get much faster, much more dependable connections for voice, data,
fax, and even video - all through a single line. There is no other
technology that comes close to delivering such communications
benefits today.
International ISDN standards were established about 10 years ago.
Since then, telephone companies throughout the world have raced to
upgrade their equipment to ISDN standards. As ISDN service
availability has spread, many millions of computer users have turned
to ISDN, and new users are coming on board even faster.
ISDN stands for Integrated Services
Digital Network
"Integrated Services" refers to ISDN's ability to deliver two
simultaneous connections, in any combination of data, voice, video,
and fax, over a single line. Multiple devices can be attached to the
line, and used as needed. That means an ISDN line can take care of
most people's complete communications needs, without forcing the
purchase of multiple analog phone lines at a higher transmission rate.
The "Digital" in ISDN refers to its purely digital transmission, as
opposed to the analog transmission of plain old telephone service. If
you're using a modem for Internet access at this moment, your
Internet service provider's modem has converted this site's digital
content to analog signals before sending it to you, and your modem
converts those signals back to digital when receiving (the same thing
happens with every keystroke and mouse click you transmit). When
you connect with ISDN, there is no analog conversion. ISDN
transmits data digitally, resulting in a very clear transmission quality.
There is none of the static and noise of analog transmissions that can
slow transmission speed.