Hi, I recently broke my android device in the rain which was not covered by the warranty so instead of buying a new phone all together ive been thinking f getting a used iPhone 3g. This phone is from a different provider but is unlocked. Once i put my sim card in will i maintain all of the features I am currently paying for on my contract? (Unlimited internet,facebook,youtube, ect)

I only ask because I put my sim card in a old flip phone (got from company while mine was out for repairs) a few months back and did not get access to the internet.