•ISDN AND OSI MODEL
•ADVANTAGES OF ISDN
•INTERFACE AND DEVICES
•MODES OF USAGE
WHAT IS ISDN?
It is a set of protocols that
combines digital telephony and
data transport services. The
whole idea is to digitize the
telephone network to permit
the transmission of audio, video
and text over existing
q ISDN - Integrated Services Digital Network
q Telephone services -> Telecommunication
q Used for voice, image and data
E - series for Telephone network and
I - series for ISDN concepts, aspects
ISDN and OSI model
Layer 1 - Physical
Layer 2 - Data Link
Layer 3 - Network
Types of channels
• Bearer channel (B-channel=64 kb/s)
clear pipe for data
• Delta channel (D-channel, 16 kb/s or 64
kb/s) call signaling information:
who is calling
type of call
calling what number
• Basic Rate Interface (2 B channels + 1
D channel (16 kb/s))
• Primary Rate Interface (30 B channels +
1 D channel (64 kb/s))
Advantages of ISDN
• reliable connection
• 128 kb/s (160 kb/s) for BRI
• 1920 kb/s (2048 kb/s) for PRI
Fast call setup
• 2 seconds
Advantages of ISDN (2)
Bandwidth on Demand
• adding new channels to the bundle of
• phone, fax, PC, videoconferencing
system, router, terminal adapter,.. each
with its own sub-address
Interfaces and Devices
phone, Fax III,...
Interfaces and Devices
• S/T (4w)
• U (2w)
• TE1 - ISDN devices
• TE2 - analog devices (need TA)
• TA - Terminal Adapter (rate adaptation
NARROWBAND ISDN (N-
The original ISDN providing data rates of
64 kbps to1.544 mbps is known as
narrowband ISDN. When ISDN was
originally designed, this range of data rate
was sufficient to handle all existing
transmission needs. As applications using
the telecommunication network advanced,
these rates proved inadequate to support
To provide for the needs of the next generation
technology, an extension of ISDN, called
broadband ISDN (B-ISDN). B-ISDN provides
subscribers to the network with the data rates in
the range of 600 mbps, almost 400 times faster
than the PRI rate.
Technology exists to support higher rates but is
not yet implemented or standardized. B-ISDN is
based on a change from metal cable to fiber-
optic cable at all levels of telecommunication.
• subscribe for PRI connections or
multiple BRI connections
• ISDN Access Server
Dial Up - Private
ISDN Access server
PC with internal or external ISDN adapter ISDN connection
Dial Up - LAN
ISDN Access Server
Integrated NT:- It is a device which forms a
boundary to the network and may be controlled
by the provider of the ISDN services.
Integrated Modem:- The term modem is
composite word refers to the two functional
entities that make up the device, a signal
modulator & demodulator.
PPP:- The telephone line provides a physical
link, but to control and manage the transfer of
data, there is a need for a point-to-point link
Normal ISDN Phone.
Advanced ISDN Phone.
Video Phone:- This is a subset of
video conferencing equipment.
BANDWIDTH ON DEMAND
A digital service that allows
subscribers higher speeds through
the use of multiple lines.
ISDN Vs Analog Telephone Line
Analog:- Voice data, one call
possible at one time.
ISDN:- multimedia data, voice data,
image graphics, can connect a pair of
telephone over existing telephone
ISDN is an effort to standardize subscriber
services, provide user/network interfaces, and
facilitate the internetworking capabilities of
existing voice and data networks.
The goal of ISDN is to form wide area network
that provides universal end-to- end connectivity
over digital media.
ISDN can brought to a subscriber premise with
minimum cost and the services available can
satisfy the need of many users.
The protocol is flexible enough to be upgraded to
higher data rates using new technology and new