But O2 do monitor the line conditions with some form of Data Line Management and adjust your sync speed accordingly.
I don't know how they perform their calculations but it does take a minimum of 24 hours to return from a bad reading to a near full speed previous value.
Sorry about the tardiness of this reply but I've only just spotted the above.
O2 monitor and "tweak" the line for up to 5 days or so after the initial connection to their service to obtain the optimum connection. After that they do not use any DLM.
They will, if there are problems, adjust Target SNR upwards if they detect instability or if the line is very good they will adjust downwards but the customer must ask for the reduction from default 6dB. This is the only management carried out after the initial connection.
Sky and I believe Talk Talk do use DLM subsequent to initial connection.
