I believe that's more of a US thing isn't it? As that's not offered in the UK.
When I had an iPhone delivered by UPS previously, they were quite adamant about the fact that that the phone had to be signed for by the person purchasing it. Deliveries would usually be left with the caretaker at my flat in a secured room, but they aren't allowed to do that with these Apple orders, so luckily I was home.
My wife signed for my 5, I think that was UKMail. I'm getting my 5s delivered at my mothers as I'll be at work, will that be a problem?