In America, the two SIM-using GSM carriers are AT&T and T-Mobile.
T-Mobile can only use it's EDGE network on an iPhone with a SIM Card needed.
To get service on your iPhone 3G after switching SIM cards from another phone, insert the new SIM card and restart the iPhone. Ensure that the SIM card is activated and compatible with the iPhone. If prompted, follow any on-screen instructions to set up your network settings. If there are issues, you may need to contact your carrier for assistance with activation or compatibility.
An Apple iPhone 3GS can be purcased unlocked without a SIM card and used with a local carrier's SIM card. Once purchased it is as simple as inserting a SIM card from the carrier of your choice.
You must have a SIM card for the carrier you want to use and the phone must be compatible with that carrier.
Of course, the iPhone 3G and/or the original iPhone will take any normal sim card; the 3G iPhone will take the 3G sim as well.
If your iPhone is unlocked, then yes, all carriers will work. But if it is locked to a certain carrier, then you will have to unlock it using a jailbreak.
yes, provided the network carrier provides the micro sim required for the phone.
Yes, you can use a Straight Talk SIM card in an AT&T iPhone, provided the phone is unlocked or compatible with Straight Talk's network. Straight Talk uses AT&T's network, so AT&T phones typically work well with their SIM cards. Just ensure that the iPhone is not locked to a specific carrier and that it supports the necessary bands for Straight Talk's service.
the micro sim is only compatible in the iphone 4 and 4s because they are the only phones that it will fit in through att
Yes, switching SIM cards in a cell phone can work if the new SIM card is compatible with the phone and the network. Make sure the new SIM card is activated and has a data plan if needed, and ensure the phone is unlocked or compatible with the carrier you want to use.
You need one with a SIM Card slot. From there, find a GSM carrier, buy a SIM card and slip it in. (T-Mobile, AT&T, and every European carrier is GSM).
A standard sim, so no microsim like with the iphone 4. Just see if your device is not carrier locked, in that case you need a simcard from that specific carrier
No. The sim card would not be inter-carrier compatible.