Are these speed estimates for FTTC conservative? Do you think I could actually get a higher downstream speed than the 53.5Mbps top figure it claims I can get?
The ranges quoted are meant to come from similar lines - which means they have a similar amount of loss (attenuation) measured between the cabinet and the DP at the top of the pole.
The figures at the top and bottom of the range are meant o match the 20th and 80th percentiles - while means 20% of "similar lines" get speeds better than the top, and 20% get worse than the bottom.
Those "similar lines" will all have some amount of crosstalk (interference from other FTTC subscribers). On a new cabinet, the first people to sign up are likely to get significantly better speeds at first ... but as more people sign up in your neighbourhood, the speed will fall - usually to within the range somewhere.
Openreach will investigate slow lines, but the range they choose (A or B) will depend on the installation method used:
- ISPs that use self-install tend to quote the B range speed, so will only investigate when your speed is well below 26Mbps. For example, TalkTalk
- ISPs that use engineer installations tend to quote the A range speed, so will investigate when your speed is well below 39Mbps. For example, Plusnet.
Don't go into this thinking you can get 60Mbps, never mind keep 60Mbps even if you start with it.