i'm sure if you upgrade, you have to use your existing sim...
depends..
if you're an existing iPhone customer, then yes.
however if you're an existing o2 customer (like I was..) then you _may_ need a new sim (depends if your sim is a "3g" one or not)
my story.
- queued for 3 hours for the phone (including 1 hour of inactivity from 8->9 am), guy in front of me got the last 16gig.. took an 8 as I don't feel i need the 16. queue in the town here had around 80 people at its longest point. i was roughly #30 inline having arrived at 730am. several people had camped overnight.
- was told i would be getting a "sim swap" and that it'd go through on friday evening.
- by mid sat afternoon it still wasn't working, tried to call the store - no answer. called the o2 national line.. was told that the backlog is being processed and that it'd be "mon at latest". my account on o2 website showed no changes.
- sun morning, got a text from a friend who got a phone with me fri morning, his was a new contract and was now working.
- lo and behold my o2 online account showed my tarriff was updated. however the new sim wasnt active, and my old phone/sim was.
so the question was.. did I just need to use my old sim? (short answer. no)
- called o2, gave them the serial number from the new 3g sim, he said it'd be "two to twenty four hours" before it worked. got off the phone. switched off both phones. turned them on again and voila. iphone now working, old phone says "inactive sim".
so they upgraded my account overnight, but didn't do the "sim swap".