Thanks so that sucks, I can;t have both the Galaxy S2 and iPhoen5 on the same phone # and just switch back and forth ?
Yes. You can. I have done this with iPhone 4 and BlackBerry 9810 and I have done this with iPhone 4 and an Android (Samsung Captivate).
1) Get your iPhone. It has a micro sim. You will be on an iPhone plan.
2) Buy a micro sim adapter on Amazon for $2.
3) On your iPhone browser, go to
Unlockit - APN Changer for your iPhone. Creat a profile with ATT as your carrier (its easy to do). What does this do? Now you can use your iPhone even if you are on a BlackBerry plan or a regular (Android) data plan. It will put an icon on your iPhone so don't be suprised to see it there, but you never have to use it so feel free to hide it in a folder somewhere.
4) Go get your Android. Tell your rep you want it activated with your micro sim (don't forget your sim adapter!). My local reps do this for me with no problem. You are the customer, after all.
5) Now you will be put on a regular data plan (for Android phones). However, since you unlocked your iPhone APN, you can move your sim (with the aid of your sim adapter) between the two phones.
Now, the only thing that can ruin this is if the SGS2 requires a "4G" sim and the iPhone 5 does not. Then I would simply get the SGS2 with its 4G sim and use a sim cutter (Yay, Amazon!) to cut it down to fit into the iPhone rather than using the micro sim that comes with the iPhone. I'm GUESSING this would work just fine but you will still only get 3G on the iPhone if it is not 4G capable, of course. I've only switched back and forth between two 3G capable phones so I have no experience switching between one that is 3G capable and one that is 4G capable.
Good luck!
Edit: I must correct myself. The 9810 actually WAS a "4G" device. I was using my 3G micro sim in it, however.