On the graph, the blue and green shaded areas show the theoretical maximum speeds you can obtain on Comstech's ADSL2+ services, at various distances from your local exchange using ADSL1 and ADSL2+ equipment.

Factors that may affect performance

While the speeds indicated on this graph show the theoretical maximum speed of the various ADSL protocols on good copper lines - with no bad joints, faulty insulation, or high speed 'interferers' (such as bridge taps or loading coils). Your actual achieved speed may vary substantially from these theoretical results, based on:

• the length of copper wire from your premises to the exchange - this is always higher than the distance 'as the crow flies'.
• the number and type of other digital services being used by other customers over copper pairs within the same cable sheath.
• the configuration and line quality of the copper wire pair between the exchange and your premises.
• electrical interference from outside sources (such as electric motors).
• the configuration of the copper wiring within your premises (ie use a central splitter for optimal performance).
• the software configuration and application on your computer (in particular how it uses the uplink back to the exchange).
• your ADSL hardware.
• the capacity of, load on, and access data rate of the destination host computer which you are accessing.

The most effective way to improve your Extreme® ADSL2+ performance is to have a licensed cabler install a good quality central splitter (available from Comstech) in your premises to use with your ADSL2+ router.

So how does ADSL2+ perform in the real world?

You don't live in a laboratory, so it's quite true that the various factors listed above will reduce your performance from the 'ideal' shown in the above graph.

Hence, in December 2006 we took a random sample 3,108 Comstech ADSL2+ broadband services. Each service was connected to an Optus DSLAM and using the ADSL2+ protocol (G992.5 Annex A ADSL2+ over POTS). We found the following distribution:

• 13.4% achieve a download synch speed of higher than 20 Mbps
• 27.7% achieve a download synch speed of between 15 Mbps and 20 Mbps
• 22.1% achieve a download synch speed of between 10 Mbps and 15 Mbps
• 23.0% achieve a download synch speed of between 5 Mbps and 10 Mbps
• 13.8% achieve a download synch speed of less than 5 Mbps

So over 63% of these customers are achieving 10 Mbps download synch speed or better ......