Can somebody please enlighten me what/where ADSL providers and Chorus do when they setup or disconnect customers? What technically happens at the exchange box from where copper wire goes to the customer's place? What happens at the provider's end, and, maybe, at the provider's exchange box?

Specifically, the topic is interesting in the following context. I recently moved house and my ADSL provider successfully connected me at the new place. The broadband worked just fine for 6 days — until the provider "disconnected" it and closed my account (the reason for this is a separate hilarious story). From the point of view of my modem, ADSL connection itself was still active; it was just the PPPoA username/password authentication that stopped working.

Now, because my account with the provider was no longer a thing, I signed up for a new one the same morning, contacted their support, explained the situation in the hope that getting me connected again would be just a few clicks for them, even though I was on a new account.

But the next morning their support replied: "...unfortunately it appears that the service at your address has already been disconnected. In order for us to be able to have you reconnected we need to submit a connection order with Chorus.". So they have now scheduled "reconnection" next week! And, by the way, my modem is still having DSL link active at the moment.