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 call your carrier and activate your sim card.
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).
Its a four digit number inside the card carrier you buy it in
the sim card is just an identifier card for the network that carries your service. there is no information stored on the card. however, the police can contact the carrier for the network and get any and all personal information that the person has on file with the carrier, provided it is within the boundaries of the law
You must have a SIM card for the carrier you want to use and the phone must be compatible with that carrier.
The answer to this questions varies by the specific hardware and carrier's involved, but generally would be rather difficult to accomplish for an average consumer. Ask the new carrier if they would be able and willing to activate the existing air card on their network - the existing card may not even be technically compatible with the new carrier's network.
No. Each carrier has allowed cell phones for their carrier. If you have a GSM carrier though, you can buy an unlocked phone to use on that carrier even if the carrier doesn't support the phone. All you do is move your sim card.
the samsung rant is a sprint phone, and the sprint carrier does not use sim card technology
Some cell phones are designed to use a Subscriber Identification Module (SIM) card, or microchip that stores subscriber data. The SIM card is issued by a carrier and provides cell service by activating any phone into which it is inserted. A locked phone, however, will only recognize a SIM card from a particular carrier. If the cell phone is unlocked, it will recognize a SIM card from any carrier. The "lock" is a software setting that keeps the cell phone "loyal" to one carrier.
It could just be that the SIM card has gone bad, They can be changed out easily by your carrier.
An air card will work overseas. It depends on whether your cell phone carrier has towers in the area.