What type of SIM card do i need to be able to use my unlocked iPhone?

I got an unlocked iPhone & I want to be able to make unlimited calls, text & a new number but what kind of SIM card will I need to get & where would I get it?

I would say straight talk but the license was pulled so you can't get their SIM anymore. An at&t prepaid SIM maybe.

The carrier plans dictate what options you get, not the SIM inserted into the phone. What SIM you need for the iPhone depends on the iPhone you are talking about.

original, 3G & 3GS - miniSIM
4 & 4S - microSIM
5 - nanoSIM

Of course you get a SIM card from any GSM carrier, like AT&T or T-Mobile.

Get a StraightTalk SIM card from Walmart and use it in your iPhone.

You can try ATT for that service.