SDSL: Step forward or back for broadband?

SDSL means new telephone lines
Another negative is that, unlike ADSL, SDSL does not carry voice traffic over the same line so that customers cannot use the phone while surfing the internet. This means that new telephone lines also have to be provisioned, with the resultant additional charges.

As Michael Philpott, Ovum's broadband analyst, points out: "You really have to have a business that can justify spending four times as much money on SDSL as ADSL and we foresee that only a subsection will need it at the moment."

But even if you are prepared to put up with the extra costs and inconvenience of altering your  phone systems, the biggest stumbling block is availability, adds Philpott. While small suppliers such as Bulldog and Easynet have been providing SDSL services for more than a year, so far this has been limited to the London area.

BT has broadened coverage to include Coventry, however, and has plans to expand to Manchester, Birmingham, Leeds, Bristol, Edinburgh, Newcastle and Sheffield during the next few years, if demand warrants it.

These limitations mean that, of a total of 3.2 million DSL business connections at the start of this year, only 374,000 were SDSL. These figures should grow to 11.6 million and 3.2 million respectively by the start of 2008, driven mainly by the SME market and the growing adoption of teleworking, according to Ovum's Philpott.

Quocirca's Longbottom, meanwhile, believes that the market will really start "waking up" and taking notice of the technology in the second half of this year. "How rapid uptake is will be based on how quickly exchanges are enabled and what value propositions the vendors put together. It could take a long time because there are so many things that could go wrong. But it only takes one company to get it right for SDSL to become the business-connectivity mechanism of the future and wipe the floor with ISDN and ADSL," he says.