When we moved house, on the morning of the move our line switched to that status. The number 17070 reported wasn't our number, it was another number. Possibly the new owners one ?...

More than likely, lots of renumbers happen remotely, could also have been a dummy ‘engineering number’ used a place holder until (for instance) a directory number gets imported from a LLU or TL service

The guys that disconnect the wires at the exchange have pretty much all been made redundant so it will probably take a while to get done.

Will the last person out please turn off the lights

Mine FTTC on SOGEA still have dial tone on it and 17070 still work but when it changed to SoGfast the dial tone is no longer work and there is no dial on 17070 nothing just completed dead on the phone line just G.fast on the broadband.