blackberry 9790 swap for white iphone 4 or 4s +

I am wanting to swap my blackberry 9790 for a white iphone 4 or 4s, my phone is on tmobile but also works on orange, as anyone who doesnt know the companies are now one, it is the touch and type model in good condition with box charger etc, hardly used as I cant get the hang of it, the iphone must be 4 or 4s & in good condition unlocked or on orange No emails just phone contact Thanks