This is some basic information for you to begin the process of purchasing/using a cell phone in the U.S. It does not contain all the information you need, but it can get you started.
Conventional phones: These phones can make calls, send text messages, and possibly take photos. They cannot access the internet. Popular brands are LG, Motorola, and Samsung. These phones cost $20 to $75. Many international students choose these types of phones.
Smart phones: These phones can access the internet and can make calls with Skype. Popular brands are Samsung, iPhone, Blackberry, and HTC. Smart phones cost from $50 to $800.
Used phones: If you are in contact with another person leaving the United States, you may buy their phone, then put your own service plan onto it. Be certain it will work before purchasing it.
Once you have a phone, you must have a service provider put a plan on it in order to use it. The providers do this by inserting a SIM card into the phone or by unlocking the phone for their services. The most popular providers are Verizon and AT&T. Others are less popular but may offer service that fit your needs.
Card prepaid plans: With a prepaid plan, you can purchase minutes on a card and manually put the minutes on your phone before you use it. If you run out of minutes, you must buy another card and put more minutes onto the phone. These plans often do not have a contract. This means you can stop using your phone at anytime without being charged a fee. These plans are cheap if you do not use your phone often.
Monthly prepaid plans: With this plan, you can buy a large amount of cell phone service at the beginning of each month. This is a prepaid plan, but you do not have to buy a card and manually put minutes onto your phone. The cell phone provider automatically does that. These plans do not have contracts or they have short contracts. Many international students choose this option.
Contract plans: These plans require you to use the service for one or two years. You must pay each month. If you decide to sign a cell phone contract, you might get a free phone. If you break the contract and stop paying, you will be charged a (often very high) fee. These plans are the most expensive.