Many iPhone 3GS owners are upgrading from earlier models, either the original iPhone or the iPhone 3G. While the setup process for the iPhone 3GS is fairly similar to that used for both earlier models, here's a step-by-step guide to setting up and using your iPhone 3GS.
NOTE: If an iPhone 3GS is your first ever iPhone, use this iPhone set up guide instead. Though it was created for the original iPhone, the setup process isn't particularly different these days.
Buying and Activation
The first step is setting up your iPhone 3GS is, of course, to buy it and activate it. You canbuy the phone a number of places and all stores selling it can also activate the phone. This means that when you walk out the door, your new iPhone 3GS will be working and able to place and receive calls. Sometimes it takes a minute or two for the cell network to recognize the phone, so you may find that a few minutes after activation your phone begins to recognize that it has voicemails and text messages that weren't apparent when it was activated. This is normal.
Upgraders will find that they don't need to swap their SIM card from their old iPhone - the activation process transfers your number to the new phone. (Don't forget, too, that once you've upgraded, you've got a used iPhone that many people will be willing to buy. If you're not already passing your old iPhone down to someone, why not recoup some cash?)
Though when you leave the store your phone will work, it won't have your songs, email accounts, or other data on it yet. To get those, you'll need to set up your iPhone 3GS on your computer.