IPhone 4 Straight Talk Sim Card

I want to order a sim card for my iPhone 4, but I don't know which one to choose or if it even matters.
So when I go to buy the sim it asks if it's a CDMA, unlocked GSM, AT&T compatible or T-Mobile compatible.
My iPhone isn't unlocked because I heard you don't need to, and it was with AT&T beforehand, so which do I choose?

How to turn off just GPS on iOS 6?

I know how to turn off location services but I want to turn off just GPS. I was able to do this on my S3 but is there a way to do it on the iPhone 5 (iOS 6.0.1)?

Iphone 4s microphone problems?

I got a really cheap iphone 4s from one of my close friends, the drawback is the microphone doesn't work. Doesn't work in phone calls or voice memos. Only way to talk to people is using speakerphone. That works fine. Does anybody know why i'm havin this problem? How do i fix it?

I want to buy an iPhone 5 off gum tree, is it a bad idea?

I want to buy an iPhone 5 off gumtree, the price seems correct with eBay prices and such. I'm just scared that if I buy it, the seller will take my cash and try claim it as lost or stolen? If I buy an unlocked phone can this happen?

How to delete photos in your iPhone photo library?

I just got the iPhone and they guy at the Verizon store transferred all of my photos from my old droid to this new iPhone. The problem is, photos I've never taken and some that randomly got there from Tumblr got mixed up with my photos. I want to delete some of them, but there's no little trashcan in the bottom. What do I do?

How to get facebook on my iphone 3G?

I have the iphone 3G and i was wonderin' how to get facebook, temple run and other apps like that. I tried to go to the app store but it said that i needed the "ios 5". What i find messed up is that my friend has the exact same phone i have, and she has the 4.2.1 software. She doesn't even know how to fix my problem. Is there something wrong with my phone or what?

How to upload my itunes music?

Well i FINALLY updated my phone. Iphone 4.however, when i try to upload my music that i bought but haven't synced it won't download and iv tried plugging it in and icloud

How to unlock an iPhone 4s without jailbreaking it?

I jusdt completely restored my iPhone, but it still will not accept my T-Mobile sim card. This iPhone was given to me by my brother, who lives in Oregon. Their network is AT&T. I don't know how to jailbreak it (for free), and I can't make calls on it.