is ISDN ?
Services Digital Network (ISDN) is a state-of-the-art Public Switched
Digital Network for provisioning of different services�voice, data
& image transmission over the telephone line through the telephone
BRI or BRA having TWO chl. With total speed @128 kbps
PRI or PRA having 30 chls with total speed @ 2mbps.
PROVIDED BY ISDN
following services are offered on a dial-up basis between two ISDN
(i) Desktop Video Conferencing on using three ISDN lines at 64/128 kbps.
(ii) High quality video conferencing by using three ISDN lines at 384 kbps
(iii) Video Telephony.
(iv) Teleconferencing which facilitates the transmission of pictures,
documents and drawings etc. apart from voice and images of the participants.
(v) High speed data transmission at 64/128 kbps.
(vi) High speed facsimile at 64/128 kbps with G4 Fax terminal.
(vii) Access to Internet with a higher bandwidth of 64/128 kbps giving
significantly improved response time and quality of service.
KINDS OF ISDN TERMINALS
being a Value Added Service, offers many supplementary features/services:
(1) Calling Line Identification Presentation
(2) Advice of Charge
(3) Line Hunting
(4) Closed User Group
(5) User to User Signalling
(6) Call Waiting
(7) Call forwarding
On No Reply
(8) Multiple Subscriber Number
ISDN telephone line is terminated on a common box called the Network
Termination (NT) at the subscriber�s premises. The Network
Termination unit along with accessories will be provided by the MTNL or can
be procured by the subscriber. The terminal equipment has to be procured by
the subscriber himself from the open market. The terminal equipment should
be TEC approved for the satisfactory working of ISDN.
OF ISDN TERMINAL
ISDN feature phone: this is a simplest type of ISDN phone which has an LCD
display and some additional keys.
(b) Terminal adapter
(c) PC add-on ISDN card
(d) Video phone
(e) G4 fax
(f) G4 fax
connection can support both voice and data.
quality services being digital right from subs, premises (end to
terminals can be connected on a single line.
speed data transfer from PC to PC is possible 64 Kbps against
existing 9.6 Kbps (6 times faster).
calls can be established simultaneously on a single pair of wires.
call set time is very short (1-2 seconds).
number of supplementary services are supported like in pots.
Identification, Call Forwarding, Call Forwarding on busy signal, Call
Forwarding on no reply, Call Forwarding unconditional, Advice of Charge,
Terminal Portability, Multiple Subscriber Number, Closed User Group.
of ISDN for Network Operators
of separate networks for different services.
use of the equipment of the digitalized telephone network,
especially the copper pair of the subscriber line.
in costs due to simplified operation and maintenance procedures.
is ISDN line superior to the phone line ?
call set-up time between two ISDN subscribers is extremely short.
signal on the ISDN line voice or data, is sent in digital mode.
signal level at subscriber's terminal equipment is independent of
ISDN subscriber can establish two simultaneous independent calls
which could be voice, data, image or combination of any two whereas
only one call is possible on ordinary telephone lines.