Ajay: We need to take the accounts system offline to carry out the upgrade. But don't worry, it won't cause too much inconvenience. We're going to do it over the weekend.
Teresa: How long will the system be down for?
Ajay: We'll be taking everything offline in about two hours ' time. It'll be down for a minimum of twelve hours. If everything goes according to plan, it should be up again by 6 pm on Saturday.
Teresa: That's fine. We've allowed forty-eight hours to be on the safe side.
Ajay tells Teresa they need to take the accounts system offline to carry out the upgrade. Teresa asks the offline time and agrees.