Both of you are correct in some ways, and both incorrect in others.
For a start, DLM on ADSL2+ and DLM on FTTC act in completely different ways. The first acts on BT Wholesale
MSANs/DSLAMs at the exchange to BT Wholesale specifications. The second works on Openreach DSLAMs in the cabinets, to Openreach specifications.
The only significant commonality between them from the end user point of view is that for BT Wholesale-based ISPs an IP Profile is applied by the BT Wholesale BRAS system for both ADSLx and FTTC when it is notified of the connection speed and applied in their backhaul.
It is not applied (so far as I know) in the Openreach DSLAMs. It is nothing to do with Openreach.
The 10-day period, as WG says, is a complete myth. On both services. On ADSLx it is used purely to calculate the Maximum Stable Rate and Fault Threshold Rate, which are set by the lowest sync during the 10 days. The actions the DLM takes during that ten days are just like they are all the time.
FTTC DLM has an initial "grace period" of 24-48 hours when DLM basically works and may take a few hours to settle from first connection, but in seriously unstable lines will cap the maximum sync in both directions to obtain stability. It can also cap the line at any future time if certain criteria are exceeded.
I don't think there has ever been a 14-day period involved for anything technical. The nearest I can think of off-hand is the ten working days Ofcom stipulate for a migrating user to change their mind. Even that isn't always 14 calendar days, as Bank Holidays are excluded as well. Not just Saturday and Sunday.
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