There is a tie cable from the PCP (cabinet) to the VDSL twin. When you order a VDSL connection the technician goes to the PCP and separates the incoming E-side from the exchange and D-side which goes to your house.
He then connects the E-side to a tie pair which goes to the DSLAM in te twin. At that point the voice and VDSL signals are combined onto another pair in the tie cable. He will then connect your D-side to the retuning tie pair within the PCP.
So, every one is actually implemented "on-demand"
M H C
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