Can I put a sim card in an iphone?

I wanted to put a straight talk sim card into an iphone. Does it have to be a straight talk iphone or can i use a different companies iphone? Or does the iphone have to be unlocked? If the iphone is unlocked what does this mean for me, future wise?

To use a sim card other than from the company in which you bought your iPhone from, the phone will have to be unlocked. That being said, you won't be able to use an unlocked iPhone with all phone carriers, so you should check with Straight Talk first. Another thing to take note of is the fact that iPhones don't use the standard SIM card, rather the newer micro SIM cards. The reason why I say to contact your service provider first is to make sure that the data plan will work with an unlocked iPhone.