Using another upgrade but can't swap SIM cards.....

[soilsample]

Hey guys,
I'm using one of the other upgrades on my family plan to get my new 4s.
Problem:
I'm using my Son's upgrade on his 3GS so I can't just swap sim cards.

Best Buy says they have to activate phone in store....

Can I go home and restore my new 4s from a backup of my old 4 and get my old # back?
Then restore his original 3GS to get his number back?

Any easy way to get this done?

 

[VOLS34]

They should be able to swap things around. Have both phones with you.

 

[VOLS34]

Also you may wanna backup & sync your 3GS & upgrade to iOS 5 that way you can take your 4S home & restore it from backup to get your contacts & such.