How can I get an iphone to replace my mom's old phone without activating it until she opens it?

Question

The guy at the store was a real jerk.  He said I could not get the new phone and delay the switch or activate it myself, that once I got her the new phone I could not leave the store without activating it and turning off her existing phone!  He was very rude about it and truly made me dislike the Apple store.  I had done this once before, but now thinking back I think I ordered the upgrade online.  He called me a liar and said I had done no such thing in the past that it was impossible.  I asked if I could do it if I just bought the phone full price and he said no.  He said there is no humanly possible way to buy an iphone that was not activated at the time of purchase, and if I wanted to keep her existing phone number there was no way to do it with her phone staying on until the day we gave her the new one that the minute I buy her the new phone her old one will be turned off.
This seems wrong and not the best marketing for Apple. 
So is he right?  Can you no longer get a new or upgraded phone as a surprise for someone?
We have to go in now before the party to do the switch so we can get her the surprise but keep her phone on (except for maybe an hour before she opens the present and hopefully she doesn't get stranded on the road on teh way to the party in that no phone service window!...)

Answer 1

I will assume you are in the U.S. (only because I don't know how this works in other countries).  I will also assume you know your mom's current cellular carrier, want to stay with that carrier, and that is a carrier that works with Apple iPhone under contract (AT&T, Verizon, or Sprint).
Certainly if an iPhone is ordered through the Apple Store online, it doesn't have to be activated until the purchaser is ready to activate it.  Activation is accomplished by iTunes when setting up the iPhone.
These days, it is possible to order an iPhone from the Apple Store online, and have it made available for pickup at the Apple Store (instead of delivering it to a home or office).
So, bottom line, the new iPhone would be ready to go with a pre-determined phone number and carrier, purchased at the (subsidized) carrier rate, and become activated when the purchaser is ready to do so by plugging into iTunes.
I think that's exactly what you are trying to do, and exactly what you have been told is not possible.  I don't believe for a minute it's not possible (given the assumptions in my first paragraph).
I hope that helps.