Over the past couple of years there has been increasing competition in the provision of high-speed internet access. This has resulted in lower prices and faster maximum speeds. Most ADSL links in the UK are provided over BT's infrastructure and BT now offers rates of 1,024kbit/s downstream and 256kbit/s upstream - and 2,048kbit/s downstream and 256kbit/s upstream if the line quality is good and you're not too far from the exchange.

More recently, the competing operators who use BT's unbundled local loop have installed ADSL2 and ADSL2+ equipment in its exchanges and now offer rates of up to 24Mbit/s downstream.

Bulldog (now part of Cable & Wireless) offers 8Mbit/s downstream and 512kbit/s upstream from a growing list of exchanges. Bulldog claims to be able to reach six million customers but not all at 8Mbit/s. UK Online and Be offer even higher rates, up to 22Mbit/s and 24Mbit/s respectively. Upstream rates are up to 1.3Mbit/s. Prices are competitive, but again the lines will have to be quite short to achieve these rates.

The existence of these services should get IT departments thinking: many companies will be able to get a significant increase in downstream speed by adding ADSL connections to their networks.

What about the reliability, though? Solid internet connectivity is vital to more and more companies. None of the ADSL services is available with a traditional service-level agreement (SLA) but prices are low, why not get two or more connections? If the failure patterns of the circuits are statistically independent, the failure probabilities just multiply up.

For example, if one connection has a failure probability of 0.001 (0.1 percent) then two will have a failure probability of 0.000001 (0.0001 percent); in other words, 99.9999 percent availability.

The snag, of course, is making sure that the connections are as independent as possible. One good way would be to use a mixture of wired and wireless services. The new wireless WiMax systems should offer rates of about the same level but the connections do not rely on the same cables in the ground.

Configuring a system with multiple, diverse connections to the internet requires nifty router work to ensure traffic is handled properly in the case of a line failure and to handle IP address issues. A specialised piece of kit such as the Flow Control Platform from Internap could help.

It's worth checking to see whether the new, low-cost ADSL services are available and adding a line or two to existing systems. It might just be possible to scrap some of those expensive leased lines with their SLAs.