zoenphlux :
ATT doesn't have a "CAP" they have a "LIMIT" on what the normal monthly rates allow. After I think 150gb/m they charge 10$ per GB extra. If they have a true cap I've never heard of it. Of course at only 6mb/s MAX on normal DSL(most of their lines still) that is actually hard to hit unless you stream video 24/7. Even Uverse is maxed out at 24mb/s and that is only if you are right at the junction according to some technitions I know. They are sticking with copper to the house still which is why it is still slow compared to most. 18 down and 3 up is the max for most people. Fastest Cable we have is 12mb/s. I live in a smaller town(bout 15,000 ppl) in GA.
ATT is killing the US from getting faster speeds.
that is what most people mean by a cap.
In the US there is no "cap" on where you can go in the white house, but certain locations will charge you a couple bullet holes.
Uncapped means you can use as much as you want and not have any additional cost or negative actions. Bandwidth caps are one of the biggest scams. an ISP's network is limited by throughput and not by the amount of data you are allowed to transfer. If they have a 10mbit network and want to give each customer a megabit, they will support 10 customers. if they were to add 20 customers to the 10 mbit network, then create a cap of 1GB of upload+ download per month, it would not magically allow all 20 users to get 1mbit/s on the 10mbit network.
The only way a cap like that can offer more customers to get fast speeds on an oversold network is if they indirectly block traffic.
Since it will be a huge uproar if an ISP blocks certain sites, and in most cases, they are not allowed to, they use indirect means to block certain traffic.
eg, you would not use netflix on a satellite internet connection because you would blow through your cap in 2 hours.
A more physical example is suppose a politician wanted to stop all air travel, without violating the right to travel clauses?, the politician could just change the regulation, on the airspace. No passenger aircrafts are allowed more than 20 feet above ground level. (then they can say, hey you can still fly, but just not so high) (in case you did not notice, modern large passenger aircrafts are unable to fly at that height)
This is how ISP's indirectly block things by making anything that would allow a customer to use the full speed being sold to them, impractical to use.