An Introduction to ISDN
What is ISDN?
ISDN stands for Integrated Services Digital Network. In simple terms, an ISDN is an all-digital telecommunications network that can carry voice, fax, computer data, video, and the like. In technical terms, an ISDN is a digital network that integrates several disparate systems, including public telephone networks, packet switching networks, and cable television, into one standard set of user interfaces.
What are the Advantages of ISDN?
- Speed: ISDN is fast. A BRI (Basic Rate Interface) ISDN line can transfer data at speeds of up to 128 kbps. A PRI (Primary Rate Interface) ISDN line can transfer data at speeds of up to 1.5 Mbps. Broadband ISDN, the next generation of ISDN, offers speeds from 150 Mbps to 600 Mbps.
- All digital: Major sections of the telephone system have been digital for sometime now. The POTS (Plain Ordinary Telephone Service) link from telephone exchange to customer, however, is still analog, which means that signals must be converted from analog-to-digital (A/D) at the source exchange, and from digital-to-analog (D/A) at the destination exchange. ISDN eliminates these multiple conversions, providing the final link in an all-digital telecommunications network.
- Reliability: Analog telephone lines are susceptible to line noise, interference, and poor connections. ISDN eliminates these problems, providing reliable connections every time.
- Connection setup time: Connecting to the Internet with a modem can take between 10 and 20 seconds. With ISDN a connection can be established in just a few seconds.
- Two lines in one: A BRI ISDN line provides two 64 kbps channels that can be used simultaneously, so you can still take incoming telephone calls or faxes while surfing the Internet. If you've ever had friends or relatives complain that you're always engaged, you'll understand the benefits of two channels.
- Cheaper than two analog lines: Compared to installing a second telephone line, ISDN can save home customers up to ¥1,450 a monthly in rental fees. A new analog line with NTT carries a ¥72,000 non-refundable fee for a subscription right. Although it's possible to sell or transfer a subscription right to someone else, with ISDN you get to keep the ¥72,000 in your bank.
- Additional telephone numbers: With ISDN you can have additional telephone numbers for just ¥900/month each, providing dedicated numbers for home telephone, business telephone, and fax.
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Created: 16 May 1997. Modified: 13 September 1998.
Copyright (c) 1998 Paul Findon. All rights reserved.