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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 equipment.

    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 3,500 yen.

    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 lines.

    (Nikkei Communications)

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    Updated: Wed Mar 17 13:20:52 1999 PDT