Could I change my blackberry to a iPhone?

I'm currently on a blackberry curve 9360 at £20.50 per month. I also have the insurance which I think is £7? Anyway I know I'm lucky to have a blackberry at such a high price but I was wondering If I could swap my blackberry for a iPhone 4s but on the same contract? Also my contract is 24 months and I think I've had it since march.

Added (1). I'm on orange: D

You would have to buy a iphone

You would have to change your contract if you get the iphone
but i don't really suggest that you get the iphone
i have an iphone and i hate it
the physical keyboard on the curve is way better than the keyboard on the iphone
i'm even thinking of switching to a blackberry
stay with your blackberry till january 2013 and upgrade to a bb10 device
they will be amazing and very different from currect blackberry devices and os
there's a full touch version of a bb10 device
the keyboard even though it isn't a physical keyboard it still is amazing
offers true multitasking
screen resolution is way better than the iphone
web browser is very good
and overall bb10 devices will be amazing and way better than the iphone
hope i helped.
tell me what you decided to do
and if you have any question you can email me at spieleranswers@outlook.com