Carriers also must address issues of efficient provisioning, billing, security and management of these services to avoid the kind of public relations nightmare that accompanied many ISDN rollouts--where services were later and pricier than anyone expected.

Analysts also contend that the widescale consumerization of DSL will force today's $1,000 price for a pair of rate-adaptive ADSL modems and accompanying central office equipment to drop to $500 to $650.

Finally, perhaps up to 40 percent of the 160 million copper lines deployed in the United States may need to be modified to accommodate DSL--at a cost some experts put at $100 per loop.

The Technological Heart Compounding these business and infrastructure challenges is the fact that two key modulation techniques are competing in the DSL space. The DMT (Discrete Multitone) technology standard, put forward by ANSI (American National Standards Institute) and the European Telecommunications Standards Institute, provides for feature-rich transmission up to 6.144 Mbps from central office to customer. Upstream transmission is set at 640 Kbps. A simpler and more readily available approach is the CAP (Carrierless Amplitude and Phase) modulation technique fostered by Paradyne, Lucent, Bell Atlantic and NYNEX.

A recent merger between competing vendors, Westell Technologies and Amati Communications Corp., is expected to tilt industry momentum toward DMT. Amati also recently announced a cross-licensing agreeme nt to share patented DMT technology with Alcatel. Taylor estimates that CAP/DMT momentum is split 50-50 in the United States, with DMT enjoying an edge internationally.

Time to market is an important issue. While CAP is implemented in products, DMT products aren't expected to hit the market until year's end, with services based on those products emerging in the first half of next year.

The Applications Conundrum Important questions persist about which business applications are best-suited to the high performance promised by DSL. Some applications--browsers, for example--have had problems in the past with regard to taking advantage of increased bandwidth. However, work is under way in the IETF (Internet Engineering Task Force) to optimize TCP for high-speed and satellite transmission. Taylor cautions that both software and hardware need to be optimized to take advantage of DSL. He points out, for instance, that some PC communication ports don't support more than 1 Mbps.

What should businesses do until such issues are resolved? Ask questions: Find out what DSL provisioning is occurring in your service area or areas. Examine costs and payback, and budget considerations entailed in DSL. Consider turning over some of the technology risk factors--CAP versus DMT--to the carrier in the form of an outsourcing agreement. Rethink remote user strategies with DSL in mind. Make pointed inquiries about line quality in your service area. Draft desktop buying guidelines that ensure that remote access desktops purchased will support multimegabit speeds. Examine applications, and determine what technology provides the best access fit--be it DSL, T1, ISDN or yet another answer.

Saroja Girishankar is executive industry editor at InternetWeek. She can be reached at sgirisha@cmp.com. Christy Hudgins-Bonafield contributed to this article. She can be reached at cbonafield@nwc.com.