How to upgrade from iphone 4 to iPhone 5?

Hi
I'm going to upgrade from the iphone 4 to the iphone 5 when it is released to the public.
I'm already on a cap so i will just renew it with the new iphone5.
I'm happy to keep my iphone4 but i want to give me son the iPhone 5.
The two phones take a different sim, how can i arrange this?

How did your carrier answer your question?

That sucks, leave it to apple to make it difficult for it's consumers. Anyway to answer your question When you activate the new phone they will put in the correct chip all you need to do is have your carrier set the new one up with is phone number and add a plan.

If you were keeping the new one and giving him the old one they can simply transfer the data on the sim chip from one to the other with a connection cable they do it every day with no issues.