Xilinx Solution Summary

Xilinx provides significant value in a ISDN modem when used to interface various ASSPs together, resolving differences in their interface control signals.

Xilinx Solution Summary Xilinx provides significant value in a ISDN modem when used to interface various ASSPs together, resolving differences in their interface control signals. ISDN Modem Block Diagram (click on a burgundy box for next level of detail or click on a link below)  System Glue

ISDN Market Overview

In the past, video, audio, voice and data services required at least four separate networks. Video was distributed on coaxial lines, audio over balanced lines, voice used copper cable pairs and data services required coaxial or twisted pair cables. This multiple plant environment was expensive to install and difficult to maintain. ISDN is different. It integrates voice, video, audio and data over the same network and cable plant with quality not available in previous switched services. It offers features such as on demand networking, automatic bandwidth and on the fly connectivity. These advanced services are available, in large part, because ISDN is digital.

The Integrated Services Digital Network (ISDN) is becoming a mainstream telecommunications network that will serve a wide variety of users' needs. Experts call ISDN the telecommunications network of the 21st century, the foundation upon which to further build the information age. With its narrowband and broadband aspects, the ISDN data highway will evolve from today's switched telephone and dedicated leased-line networks to become a unified global network carrying voice, data, video, interactive pictures, and other services to homes and businesses.

Once touted as the ultimate subscriber technology, ISDN has seen slow deployment until recently, due to lack of standardization and high cost. Most Regional Bell Operating Companies (RBOCs) deliver ISDN as a dial-up, metered service. This means that during business hours users are charged for each minute the ISDN connection is operating.

ISDN has also lost appeal as analog modems have reached the 56 Kbps level. Modem suppliers now provide software that lets users use two 56K modems as a single 112 Kbps connection, close to the data rate available from an ISDN connection.

At the other end of the spectrum, DSL and cable modem services are delivering bandwidths that are an order of magnitude greater than ISDN. While ISDN will not be disappearing any time soon, all projections indicate that growth in the ISDN market is flattening. It is expected that ISDN will be relegated to applications where cable modem or DSL service is not available. Analysts indicate there are approximately 2 million ISDN lines deployed in the U.S. This represents approximately 1.1% of all lines.