[graf_von_anonym]

There are tools that allow historical usage to be determined from a MAC address, and there are tools that show the stability of a connection. If the signal levels and flap count and the like are recorded at point A, and then analysed a week later at point B, then for all intents and purposes the connection has been 'monitored' over that duration. It's maybe minimal, but it's efficient and useful.

The tools to which I refer can show how frequently (if at all) the modem disconnects, the traffic that goes through the modem, and historical state changes from the modem as well as some measure of the variation of signal to it. So it's at least equivalent to monitoring it for a week, though it isn't as if someone will be looking at the modem constantly.

Of course, there is a chance that it's what one might call "a lie", but I suspect Virgin have higher priorities than fibbing to your dad.