Need to know about an Unlocked Iphone 4s?

I was wondering if i bought an unlocked iphone if I could use it with a Straight Talk sim card?

Yes, as long it is GSM and unlocked, you can use it with straight talk. I would suggest checking out Ptel though. There you can get 4g connectivity.

Yes but make sure the phone you are purchasing is from gsm.
basically a phone that was from at&t or t-mobile because those are gsm signal carriers.

Yup if it is unlocked you can use any GSM carrier to it… If not you need to get the Iphone remote unlocked from any commercial vendors online like http://www.wickedunlock.com in order to access other carriers