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| CIAJ Proposes ISDN Technology for Low-Cost Internet Access
March 18, 1999 (TOKYO) -- A new technology called IP over ISDN is likely
to lead to full-time access to the Internet at a low cost, according
to the Communications Industry Association of Japan (CIAJ).
|The know-how is based on existing technology for integrated services
digital network (ISDN) lines. It also allows local telephone exchanges
to be bypassed, thus making possible inexpensive, full-time connections
to the Internet with data transmission speeds of up to 100kbps.
A special committee under the CIAJ established with the aim of devising
ways to make Japan's telecommunications industry more competitive, recently
presented information on IP over ISDN. The technology is now under study.
The CIAJ committee presented its views to a special panel under the
Ministry of Posts and Telecommunications, which was set up to examine
options for constructing next-generation networks.
The CIAJ is an industry association comprising more than 250 manufacturers
and other companies involved in the telecom sector.
According to the CIAJ's calculations, IP over ISDN technology would allow
users to obtain full-time Internet connections for a fixed monthly charge
of about 3,500 yen (118.22 yen = US$1). This is good news for those
individuals and SOHO users who subscribe to ordinary dial-up-network
services and must pay relatively high charges.
The basic idea underlying IP over ISDN is as follows: First, the user
installs a new type of terminal adapter (TA), and then two ISDN B-channel
lines are laid to link that adapter to another adapter installed in
the local telephone exchange to provide a 128kbps ISDN connection. The
TA encodes telephone voice data at 8kbps and fax data at 14.4kbps. Thus,
even if both the telephone and the fax are utilized at the same time,
sufficient bandwidth remains to allow for 100kbps Internet access.
The adapter in the telephone exchange is installed on the user side of
the subscriber exchange equipment and can differentiate between ordinary
voice data and Internet protocol (IP) data. It routes voice and fax
data through the exchange, as usual, and diverts IP data to the Internet
network bypassing the exchange.
Low-cost, full-time Internet access is facilitated because IP data is
directed to the Internet before it reaches the telephone company's exchange
Although the technology is called IP over ISDN, it doesn't employ standard
ISDN technology. No special ISDN exchange equipment is used, because
it is considered too expensive, meaning that ISDN technology is only
evident in the lines that connect between the user's TA and the adapter
in the telephone exchange.
This is another factor that enables the CIAJ group to make a low estimate
for full-time line charges.
Using ordinary copper cables, the line charges are calculated to be 1,750
yen, or the same as the current basic charge for using the phone. Then,
charges for the Internet backbone services are added (for these calculations
they were assumed to be 1,750 yen; or about the same level as current
charges for dial-up-network connections). The total is estimated at
A new type of TA for use with IP over ISDN will likely be built by adding
both a digital signal processor (DSP) and an application-specific integrated
circuit (ASIC) to an existing ISDN TA. For this reason, its development
is expected to be quick, and it should be priced at around the same
level as the current type of TA for a standard ISDN.
Another new technology, called xDSL (digital subscriber line), which
also utilizes ordinary copper telephone lines, is attracting substantial
attention as a means of providing Internet access to individual households.
An advantage of IP over ISDN is that customers will be able to continue
to use it even if NTT's lines are upgraded from copper wires to optical-fiber
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