I am now waiting since December that my ADSL line is switched to the rate adaptive mode (RAM). Theoretically it is possible. Unfortunately the reality does not agree to this (yet).
Luckily I am not a normal customer, I know a technician which works for my ISP. He could switch the line without problems, but the next update of the system (which happens from time to time) would cancel this again, as each update “resets” the status to what is recorded in the DB. The problem is, that he can not switch my line to RAM in the DB (actually it is not him, he is a network technician not one of the sales people with access to the DB-interface). I am not the only customer where this is not possible. So far they where not able to see a pattern.
Currently there are two colleagues of him, a friend of him and me which he has as good examples where it does not work (there are more, but those are “just” regular customers). We are now his toys, he wants to find out how to convince the system to switch to RAM in those cases. This needs a while, as parts of this need to go the official way until he sees if it works or not.
I am very happy that I am not just a normal customer. This way it is much more transparent for me.