Integrated Services Digital Network (ISDN)

OVERVIEW

These Web pages are intended to answer commonly asked questions about the current telephone systems and ISDN capabilities. This information will help the NIH community to understand the telecommunications services available through the Division of Network Systems and Telecommunications (DNST). It is our mission to assist your organization in making the best decisions for its present and future telecommunications needs. You are encouraged to call the NIH Help Desk at 301-435-HELP (301-496-4357) for additional information, consultation or assistance.

WHAT IS ISDN?

ISDN is a set of telecommunications standards that enable digital voice, data and video to be sent over a single telephone line, at speeds much faster than previously possible. ISDN can be thought of as a large information pipe that integrates services. ISDN provides a single, common dial access link from the user's desktop or workstation to digital network services.

ISDN's unique architecture gives you the advantage of two (or more) lines in one, without the additional expense of a second line. Using existing copper telephone wires, ISDN expands the capabilities of ordinary phone lines, providing you with up to three channels -- two B-channels and one D-channel -- instead of the usual one. The B, or "bearer", channel can transmit voice, data, video, graphics, and images at speeds up to 64 kilobits per second (kbps). B-channels are flexible, and can be used separately for independent transmissions (such as voice on one channel, and data on the other), or dynamically combined to create a single 128 kbps path for higher speed data applications (such as desktop video). More than two B-channels can be combined for even greater bandwidth. The D, or "delta" channel, is a 16 kbps channel used for signaling the NIH digital switch to generate calls, put calls on hold, activate features and use packet data to access the ISDN modem pool. It also receives information about incoming calls, including the telephone number (Caller ID) of the caller.

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ISDN LINES

There are two types of ISDN lines: Point-to-point and Multi-point. Point-to-point lines have one telephone per line, while Multi-point lines can have multiple telephones per line (subject to cabling limitations). Most NIH users use the Multi-point ISDN configuration. All ISDN voice lines are feature rich and include Caller ID, Transfer, Conference, 30-Number Speed Calling, Call Hold, Call Pickup, and Call Forwarding at no additional charge. Voice Mail is available at no cost, and ISDN provides a visual message-waiting light on each ISDN set. ISDN data lines include B-channel data up to 64 kbps, and D-channel data up to 16 kbps.

ISDN EQUIPMENT

ISDN compatible equipment must be used for all ISDN connections. This equipment includes:

• TERMINAL EQUIPMENT 1 (TE1) is a telephone set specifically designed for ISDN, such as a digital ISDN telephone. The Office of Telecommunications Management offers 3-button ISDN sets (8503 voice-only terminals), 10-button ISDN sets (8510 Terminals), 20-button ISDN sets (8520 voice/data only terminals), for use with the ISDN lines. The 8510 terminals come with a two-line display, built-in Speakerphone, a Mute button, Hold button, Conference button, Transfer button, Redial button, and Drop button. The 8510 Terminals also come with a 30-number Speed Call capability built into the display. The 8520 set has the same features as the 8510 set, except the display is seven lines as opposed to two lines, and the Speed Call capacity is 144 numbers. Each ISDN set must have an individual Primary Directory Number (PDN). A PDN can appear on someone else's set as a Secondary Directory Number (SDN) for call coverage applications.
• NETWORK TERMINATION INTERFACE (NT1) is required for each ISDN line. It converts the two-wire ISDN line from the digital switch to a four-wire line connection to a station set. While the NTl can be a stand-alone device, it is normally rack-mounted in the telephone closet. In some instances the NTl may be integrated into the TE1.
• POWER SUPPLY Each ISDN telephone terminal requires a separate power supply, While this can be a stand-alone device, it is normally rack-mounted in the telephone closet. In some instances the power may be integrated into the TEI.

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TYPES OF ISDN SERVICES USED AT NIH

• Circuit Switched Voice, used for local and long distance voice calls (over a B-channel).
• Circuit Switched Data, used for high speed dial-up data, video, graphics, and images (over one or more B-channels).
• Packet Data Network (PDN) service, used for basic PC data applications (over the D-channel).

TYPES OF ISDN APPLICATIONS USED AT NIH

• Voice Communications incorporating Electronic Key System features.
• Video Conferencing.
• Remote LAN Access (Telecommuting).
• Interactive Data Exchange (File Transfer, Screen Sharing).
• Graphics and Imaging.
• Modem Pooling.

WHY ISDN?

• No limitations in size of system.
• End-to-end digital connectivity.
• Multiple call appearances.
• Shared call appearances.
• Incoming caller identification.
• Protection from obsolescence.
• Voice/data/video on one line.

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ISDN Telephone Service at the NIH:

ISDN Lucent Telephone Model 8510 is the type of telephone that most people use for ISDN service at NIH.
(This model is discontinued. We are now installing the ISDN ToneCommander Model 6210 and 6220)

ISDN ToneCommander Telephone Model 6210 and 6220

ISDN Fujitsu Telephone Model 9912 and 9924

ISDN Quick Reference User Guide

ISDN Modem Pool Information

SUMMARY

ISDN is now the standard in telecommunications deployments. ISDN provides you with a simple, convenient solution for voice, data, and video needs. It is flexible and cost effective. ISDN can help eliminate the need for separate lines for telephones and modems. ISDN offers digital, end-to-end connectivity, with no growth restrictions. Finally, ISDN can tie together geographically dispersed locations, since all ISDN lines are served from the digital switch.

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