So though removing to complicated in to the details, here’s the lowdown. I have an iPhone 3GS. I am not elligle for an upgrade. My father, who is on the same devise however, IS. I would get the iPhone 4 regulating his ascent and he’s peaceful to take my 3GS. Obviously, given the iPhone 4 uses a micro SIM, I can’t only cocktail my SIM in to which phone. That’s flattering good established. And I’ve been celebration of the mass on what the most suitable thing to do is. I’ve review this in an additional subject post:  “I only got the latest phone off the lorry and rushed to AT&T to re-assign numbers on all the SIM cards (my mother could upgrade, I could not). BUT DON’T DO WHAT I DID. The phones come hard-coded with the series which you’ve put in for eligibility of upgrade. So YOU MUST ACTIVATE THE PHONE WITH THAT NUMBER FIRST. THEN, we can go to or call AT&T to have the numbers re-assigned to the suitable SIM cards. It’s not a complaint to re-assign. They won’t discuss it we to stay on the strange phone or anything. But, we MUST ACTIVATE WITH ORIGINAL NUMBER, sync it up, THEN we speak to AT&T to get things substituted out. ”  So I’m receiving which to heart given the man has had a lot of problems given he didn’t turn on the SIM first. That’s all cool. But I’ve additionally been celebration of the mass things here and there which contend something similar to “Be ready to give the wireless series we wish to activate, the comment holder’s SSN and shipping ZIP code.” and “You can send your stream phone series to iPhone, or get a latest one.” These have been both instructions for activating around AT&T’s website as good as by iTunes.  So which got me meditative is this: I will be grouping the phone by Apple’s site. After I embrace the phone, during the activation process, is it starting to ask me what series I wish to use? It’s been perpetually given I’ve had to turn on with my 3GS and I never unequivocally paid most courtesy to it before. If it does, can I only turn on it regulating MY number, creation my dad’s aged SIM still active, vouchsafing us barter though carrying to revisit AT&T? Does any one know?  UPDATE: After only a couple of mins some-more of snooping (I couldn’t FIND this before), I found THIS for any one wondering: http://www.wireless.att.com/learn/articles-resources/iphone4upgradesupport.jsp Looks elementary enough! Sweet. If any one still wants to import in, feel giveaway though, though I competence have only answered my own damn question. Sigh.