It sounds to me like a misinterpretation - While the CC is indeed wrong, most of those answering are also misinterpreting the rules.
In this case, the ISP is supposed to provide up to 4.0mbit/s, but no less than 80% of that speed up to the ISP node.
What this DOES NOT mean is that your download speed will always translate to being between 3.2 and 4.0mbit/s.
What this DOES mean is if you have a plan that is 4.0mbit/s, then the speed that the cable going between your house and the local ISP node should support at least 3.2mbit/s - when you check the status of your connection on your
ADSL modem, your line rate should be synced to no less than 3355443bps or 3277kbps if you are on a 4mbit/s plan, and if they ran a line test between the DSLAM and your modem, they should get at least this speed.
On the assumption that you are using ADSL, this translates more or less directly in to two basic things:
[*]Distance from the ISP's equipment (3.2mbit/s I think would be about 4km, and we're not talking physical distance, we're talking cable distance) and
[*]Quality of the installation - that is, cable quality, bends, loops, kinks, shielding, pvc coating damage etc and environmental factors like interference on unshielded cable, secured and properly fitted connectors, protection from water and pollutants etc.
[/list]The reason that it is this way is that you can't have a maximum contention ratio of 1:50 at the network border (that's 2% of the promised speed, or a little over 20 kilobits per subscriber for every megabit the ISP has available) and then simultaneously expect to deliver 80% of the promised speed to all of your subscribers, otherwise essentially ISPs would have to provide 1:1 contention to their subscribers which simply doesn't happen.