ISDN (Integrated Services Digital Network) is a circuit-switched telephone network system, which also provides access to packet
switched networks, designed to allow digital
transmission of voice and data over
ordinary telephone
copper wires, resulting in potentially better
voice quality than an analog phone can provide(http://en.wikipedia.org/wiki/Integrated_Services_Digital_Network). ISDN is a set of CCITT/ITU
standards for digital transmission over ordinary telephone copper wire as well
as over other media. Home and business users who install an ISDN adapter receive web pages at up
to 128 Kbps compared with the
maximum 56 Kbps rate of a modem connection. ISDN requires adapters at both ends
of the transmission so your access provider also needs an ISDN adapter. In many
areas where DSL and cable modem service
are now offered, ISDN is no longer as popular an option as it was formerly ()http://searchenterprisewan.techtarget.com/definition/ISDN.
ISDN is the original high-speed
internet service. It sparked the high-speed internet development between
service providers during the 1990's and, of course, revolutionized internet
use. Much like its predecessor, the dial-up internet service, ISDN utilizes a
phone line. In fact, it set the standard for telephone data service.
ISDN internet service was the
improvement upon dial-up, and it also paved the way for DSL and cable-modem
internet service thereafter. It can be considered the step of internet
evolution that lies between dial-up and DSL/Cable. Modernizing internet use and
bringing high-speed access inside the home, ISDN became the standard by which
rival broadband internet service providers competed. Although ISDN internet
service still exists, like the dial-up connection it is being replaced by
faster and cheaper services that the broadband companies are providing.
Regardless, broadband high-speed internet service is still compared with ISDN
today since they both represent the standard of their times.
There are two
levels of service: the Basic Rate Interface (BRI) and Primary Rate
Interface (PRI). BRI intended for the home and small enterprise, and thePRI,
for larger users. Both rates include a number of B-channels and a D-channels.
Each B-channel carries data,
voice, and other services. Each D-channel
carries control and signaling information.(http://searchenterprisewan.techtarget.com/definition/ISDN)
ISDN in concept
is the integration of both analog or voice data together with digital data over
the same network. Although the ISDN you can install is integrating these on a
medium designed for analog transmission, broadband ISDN (BISDN) is intended to
extend the integration of both services throughout the rest of the end-to-end
path using fiber optic and radio media. Broadband ISDN encompasses frame relay service for high-speed data
that can be sent in large bursts, the Fiber Distributed-Data Interface (FDDI),
and the Synchronous Optical Network (SONET). BISDN is intended to support
transmission from 2 Mbps up to much higher, but as yet unspecified, rates.()http://searchenterprisewan.techtarget.com/definition/ISDN
The advantages of
having ISDN internet service definitely lies in the data lines themselves. Not
only do you have constant data speed via these lines, each bearer channel runs
at 64 kbit/sec with the ability to be combined to reach greater speeds. ISDN
internet serviced also allows for multiple data transmission, so telephone
calls and data downloading are no longer mutually exclusive. The disadvantages,
however, is that the digital clarity of ISDN voice communication and its speedy
data transmission come at an extra cost. ISDN is billed like a phone line, but
with an added cost for service. And although its operational distance from the
ISDN central office is greater than that for DSL, its terminal adaptor is more
expensive than DSL or cable modems. While this equipment and service continue
to remain costly, it is leaving the way open for other internet services, like
broadband, to quickly replace ISDN's share of the marketplace.
