Remember about 15 years ago if a customer was complaining of slow speeds on their dial up, getting about 5k out of their 56k modem, it would usually mean they were on DACS. Customer Service would look at the billing history for the other customers off that DP. If there weren't loads of 0345, 0845... numbers it meant they didn't use dial up. A DACS rearrangement would be carried out and the customer complaining of slow speeds would be taken off the DACS and would start getting blistering speeds of around 44k