Originally Posted by
notquiteaff
Seems a bit ... odd. They can't knock on the door because that would be disturbing, but they can ring the phone?
I think if room service was ordered, a quiet knock (to maybe avoid waking up a sleeping kid) would seem reasonable.
I think it's because a phone call is less intrusive (i.e. easier to ignore) than a live person at your door. The same happens to me. I sometimes forgot to take the DND sign off the door and I get a phone call from housekeeping.