The only major ISP in the UK which has complete freedom is Virgin Media. They own and operate all the hardware in their network and deliver the end product to users. There are no intermediaries or re-sales of equipment or bandwidth going on. The downside is that their coverage is EXTREMELY limited.
In contrast, pretty much every other ISP uses BT Wholesale's equipment at some stage. Some ISPs (such as Be and Sky) have chosen to get around some of this by installing their own equipment in your local telephone exchange in a process known as "Local Loop Unbundling" (LLU).
Many of these LLU ISPs have also chosen to forego ADSL and use a newer and more sophisticated technology known as ADSL2+. This can deliver faster speeds and by using LLU the ISPs are able to significantly reduce the amount of money they pay to BT for use of their network and often this means the prices will be lower.
However, the massive downside is that LLU is also extremely limited in its coverage. Like all of the technology decisions in this country, the urban areas get it first and everywhere else has to wait... and wait... and wait. In my area we have neither LLU nor Virgin Media. The maximum connection speed available here is 8Mbit/sec, limited by ADSL technology.
The problem for ISPs who do not LLU or Cable is that they have to rent hardware from BT Wholesale. This is EXTREMELY expensive and many choose to offset the cost by allocating a massive number of users to each piece of equipment purchased. They believe that there is no way that all of their customers will be using their connection at the same time and even if they were then there would not be constant data throughput (some would be downloading web pages while others were reading them etc).
As a result, we have to be limited. There's no other way around it - if people are allowed to download as much as they like, then a minority of users would completely monopolise all of the ISP's available bandwidth. That said, I think the current usage caps (whether express or implied) are entirely reasonable. I am a heavy user, but I can't understand how people can actually break some of these limits. I've seen people complaining that 50GB per month is not enough. That's ridiculous.
If you are choosing an ISP, visit http://www.samknows.com/broadband/search.php and type in your phone number/postcode. Pay particular attention to the LLU providers available in your area as these will likely give best price and performance. I recommend Be or O2. If you are an O2 mobile customer you get a discount of £5 per month.
Note: BT Wholesale is best considered to be a separate company to the Retail side of BT which sells its product to end users. I believe anti-competition law prevents BT from giving favourable treatment to its own ISP.
) but they support throttling.
