I don't believe any carriers still sell the iPhone 3GS or older, especially considering they offer the iPhone 4 now for free (with contract).
The iPhone 3GS is only available on AT&T, but newer models are available on more carriers.
You don't need to be jailbroken now that the iPhone supports most carriers. The iPhone 4 is physically unable to switch from GSM to CDMA carriers anway.
There are many shops that sell the iPhone 4s. All of the majour cell phone carriers will have them, but you can also purchase one online through the Apple store. And at major retail stores like Walmart, Futureshop or Best Buy.
Right now you can get the iPhone through AT&T and T-Mobile. All you do is order a sim card and you can use T-Mobile on your iPhone. WHen it will be able through other carriers some people say will be in January when the iPhone goes to Verizon, and October when it goes to Sprint.
You can get an iPhone at the Apple store, through carriers, or online or "brick-and-mortar" retailers.
The Work on some Different Carriers.
Nowadays, there are tons of way to sell an Apple iPhone. For starters, there are plenty of trade-in and buyback programs offered by wireless carriers, online retailers, and others. A person who owns an iPhone can even sell their device through third party sites like eBay, Amazon, and Craigslist. There possibilities are limitless when it comes to selling a smartphone. In the end, a person could simply just sell their device to a friend or family member.
no, they are the exact same phone just with different carriers.
There are a number of carriers who will sell you a prepaid iPhone. The monthly cost is about half the price of an iPhone on contract, but you will pay substantially more for the phone itself since you do not receive a subsidy in exchange for accepting a long-term contract. Also, you'll typically get an older-model iPhone when you buy a prepaid no-contract phone.
Here's a simple fix: SWITCH CARRIERS!!!!!!!!!
Well you technically can use a SIM Card for the network of you have an unlocked iPhone, but in most cases, you will only have access to the EDGE (very weak) network for carriers that run AWS bandwidth like T-Mobile.
about 2 or 3 hundred dollars