I have just signed up to go back to Sky for my telephone and broadband service after 15 years with cable. I have just realised however that the BT box in my house no longer has any wires attached. Will the guys from Openreach realise this when they do their checks? or will the box in my house show as live from the junction box outside? Seems like a stupid question but I dont want them thinking all is ok and not actually coming into the house, thus leaving me without a phone!

they will assume everything is ok your end

Yeah you`ll probably have to tell them although having said that, im pretty sure they check at their end and can tell if the socket is live or not.
Looks like a £130 charge coming your way

As long as you are only signing up to sky with 1 box, you can pay a £25 charge which allows you to have sky without a phone line.

Multiroom MUST be connected to a phone line though (more than 1 box)

Wont do him much good for his broadband tho