ISDN Connectivity by Jeff Newman and David Willis Integrated Services Digital Network (ISDN) is a service provided by most telephone companies that allows high-speed digital communication across already-existing public telephone network facilities. This high-speed service can connect a wide variety of equipment in several ways--making it an ideal medium for integration into existing wide area networking infrastructures that have outgrown their traditional plain old telephone system (POTS) bandwidth requirements. ISDN is the next logical step for connectivity of sites over the wide area that need more bandwidth and reliability than POTS connections, but don't need the volume of bandwidth and cost of very high-speed dedicated links such as frame relay or T1. Nothing comes for free. Most of the solutions to our problems that appear too g ood to be true either are too good to be true or they come at tremendous sacrifices. In the case of networks, the solutions usually come at the sacrifice of funding, flexibility and reliability of the technology that we are implementing. Although it has taken ISDN years to evolve into a reality, ISDN is now popular for being one of the most uncompromising solutions to wide area connectivity and remote access, and it will hold that status for some time. ISDN, however, is not too good to be true. It is not the easiest technology to obtain, implement or manage. To be an effective remote access or wide area network solution, it requires careful planning from start to finish. In the following article, we will analyze the most common types of ISDN, its applications, requirements and the necessary equipment. Whether it is single-user remote access or LAN-to-LAN connectivity, ISDN will be explored here to help you develop a concrete formula for choosing and implementing ISDN into your current network. What ISDN Is: BRI and PRI Why ISDN Instead of POTS or Dedicated Leased Lines? Problems With ISDN ISDN Applications Choosing the Equipment Planning for ISDN Updated May 16, 1996 Print This Page E-mail this URL