ISDN (Integrated Services Digital Network)
is digital communication service operating through the existing telephone
infrastructure. We also call it Digital Network of Integrated Services.
ISDN provides for the following:
Data transfer speed
up to 128 Kb/s, while classical analogue modems allow maximum speed
of 56 KB/s.
connecting time. With the classical modems, that speed is 30 sec, while
with ISDN, it is less than half a second.
Basic Rate Interface (BRI) may be interesting for most users, including
companies and general public. It allows the user to make a phone call,
and to be on Internet at the same time. How?
Basic Rate Interface
(2B+D) divides classical telephone line into three digital channels, two
B and one D channel. It is possible to use each of these channels separately,
where B channel serves for data transfer at speed 64Kb/s, and D channel
for dialing up and canceling phone calls, control signal transfer etc.
Hence, it is possible to make a phone call through one channel, and read
e-mail messages from your mailbox. Customers using BRI may require a permanent,
so called semipermanent connection,
capacity 64 or 128 KB/s. It enables them to switch to the category of
permanent line users. It means that a user pays fixed telephone charges
to Telekom per month, while Infosky charges are paid per traffic actually
Primary Rate Interface (PRI) provides 30 access channels, equally
available to the basic ISDN users and to the users accessing through analogue
Primary Rate Interface
is also used for Infosky access lines, which enables ISDN access on our