There are well over 40 different terminal adapters to choose from at this time, with more being released as ISDN becomes more popular. Pricing varies a great deal on the current line of terminal adapters. The low-end terminal adapters are selling via mail order for $99, and the high-end terminal adapters are selling for $700 to $800. Routers for ISDN, which allow a network to connect to an ISDN connection, have come down in price as well. Most routers were initially targeted at very large networks and can cost well into the thousands. Routers for ISDN targeted at the small office, home office, and telecommuter, and designed to connect to a small network, have a price range of $300 to $500, and higher.

Before you rush out and purchase a terminal adapter or router, you should make a few queries of your ISP and your regional Bell or ISDN provider. There are three issues that are paramount in matching your terminal adapter to your ISP or network router: switch type, the dynamic allocation method used, and compression schemes supported. If you are connecting through your ISP for ISDN service to the Internet, and have a 2B+D setup, you want to ensure that the protocol used by your ISP for the dynamic combining of channels is supported by your terminal adapter. You will also want to ensure that your terminal adapter uses a compression protocol that is completely compatible with your ISP.

By ensuring that those criteria are met, you will have a very efficient ISDN system that allows you to recover expenses over time because of the increased data transfer rates your equipment can achieve. What follows is a look at several different terminal adapters. We do not endorse any particular make or model but provide this information as a service for you. Remember, the manufacturers of ISDN terminal adapters are continuing to bring newer and better terminal adapters to market all the time. Do some research before you purchase your digital modem, and you will be very pleased with yourself and the increased performance of your terminal adapter.

Because technology is changing so rapidly and companies are constantly merging, some of the terminal adapter names and prices can change in a heartbeat as the companies jockey for market share, so we are providing a general price range along with basic information on the particular terminal adapters.