DACS units were traditionally used to run two telephone lines over a single standard copper pair. The unwanted side effect of this is that ADSL will not work on a line with a DACS fitted. Openreach has made a further policy change on top of what was announced in August 2006.
The new policy should see more DACS units being removed where people order broadband, irrespective of whether it is via BT Wholesale or a LLU provider. DACS units may still be put onto new telephone lines (where it is not a simultaneous provide order - which means a phone line and ADSL are ordered at the same time) where using a DACS unit is the only way to meet the Customer's Required by Date.
In the past we have seen some broadband providers rejecting orders that have DACS units on them without forwarding them to BT Wholesale or Openreach for evaluation, so if a provider rejects your order very quickly suspect they've rejected based purely on the results of what www.btwholesale.com/getbroadband says. As a general rule it will take the relevant BT departments up to a week to look into issues like DACS units and TPON.