Banking on ISDN

In "ISDN: Give Up and Go?" (February), you insinuate that ISDN is dead because ADSL and Digital Simultaneous Voice and Data (DSVD) are going to take its place. While ADSL works well under certain conditions, how many telephone subscribers meet these restrictions: No further than 12,000 feet from the phone company's central office; no load coils; no fiber optics? The phone companies have been trying for 10 years to get the copper out of the local loop.

Anyone who has a 28.8-Kbps modem can tell you it's very unusual to actually connect at 28.8 Kbps. DSVD works great when you can take a 9-Kb channel from 28.8 Kb, but if you take it from a 19.2-Kb channel, the system starts crawling. ADSL and DSVD may look good on paper, but they are the last vestiges of a dying technology.

Dave Breeding
bluadept@e rols.com

Our point was not that we'd all be tossing ISDN in favor of ADSL or DSVD but that there are other technologies in the works that might meet some immediate needs. Obviously, ADSL will not be good for applications that require two-way traffic exchange, and DSVD is also limited. But both might appeal to niche markets: ADSL for video on demand or Web browsing, and DSVD for customer support. Given the lingering lack of ISDN service in many regions--I've been waiting for ISDN in my part of New York City for three years--these technologies may be your only choices.--Sal Salamone, news editor