If you need a basic understanding of shit to do with phones, check this out, I typed it up a while ago. In the beginning, before mobile web was even conceived, there was one standard technology...landline phones. Thankfully, with the invention and increasing affordability of mobile phones, we can all be connected at any given moment. This is cool, except that most carriers make you sign your life away for 2 years and most phones either die or get outdated within a year. So, what's a person to do when he/she either needs or wants a new handset and doesn't want to fork over 2 more years of their life or an absurd amount of money by going to a corporate store? Well, you have a few choices. Before we dive into that, we need to understand a little about cellular spectrums. In order to buy a new phone, you need one that will run on your network, unless you really want to bail and possibly pay up to $275 for violating you contract terms. We'll start with Cingular and T-Mobile, which run on the GSM (Global Standard for Mobility) standard that 70% of the world uses. This is different from Verizon or Sprint or Nextel. Verizon, Sprint and Qwest who use the CDMA (Code Division Multiple Access) network. Nextel uses a technology called iDEN. CDMA is used on North America and South Korea. iDEN is only in the USA. Then, we have a fourth type of network, the MVNO. MVNO (Mobile Virtual Network Operator) providers work by leasing spectrum from the big companies. Services such as Helio, AMP'D, Disney and ESPN Mobile all run off of Sprint and Verizon's massive CDMA networks. Boost Mobile uses Nextel's iDEN network, which is why you can use the grammatically incorrect "Where you at?" fragment to "chirp" other Boost clients instantly. This is called PTT, or Push-to-talk. "But GearHead!" you shout. "What the hell does this have to do with little old me?" Glad you asked. There are other providers that run GSM. In America, it's just Cingular and T-Mobile. There are many other providers worldwide that use this standard too. Vodafone, 3, O2, Orange, Fido and Rogers are just a few. There is something about GSM that is unique to it: it uses something called a SIM card. A SIM (Subscriber Identity Module) is what has your phone number stored on it. You pop this into a GSM phone and whamo, you have your number being routed to that phone. THE FOLLOWING REFERS TO GSM TECH ONLY. The problem that you run into is called "locking." This is a practice, invented by greedy capitalists, that allows a phone only to accept a SIM card from a certain provider. For example, if you buy a new RAZR V3 from Cingular it will be locked to Cingular so only Cingy customers can use it. "Well damn. Sucks to be a consumer, huh?" you're no doubt thinking. Thank God the market reacted very strongly to this practice and required phone manufacturers to put a backdoor to this in: the subsidy unlock code. This 8 digit number will allow your phone to use any SIM card you want. Entering this code is known as "unlocking." There are very easy ways to obtain unlock codes for most phones, you can find a place on the web that will send you the code for about 5 dollars (or go to a shop in town to do it for the same price). OK, so, what you need to find is either a phone locked to your provider or a phone that is unlocked. It can be "branded" to anything. Branding is the actual hardware and firmware's logos and proprietary shit. For example, my PEBL. It says "T-Mobile" on the battery cover and used to have T-Mobile created menus for easy access to their proprietary downloads. My phone would be called "T-Mobile Branded". So, when you are starting your hunt on eBay or Google, make sure you are bidding on an unlocked or locked phone that works with your provider. If you are indeed bidding on an unlocked phone, take a second to look at the bands it operates on. There are 6 bands that phones run on in the GSM world: 850 MHz, 900 MHz, 1800 MHz, 1900 MHz, UMTS and HSDPA for high speed data. Since you will be using this phone in the US, there isn't a need to worry about the last two bands (they are used for early 3G, or third generation, high speed data deployment in Europe and some Cingular networks in select areas). The bands that US towers operate on are the lowest and highest of the voice bands: 850 MHz and 1900 MHz. Most phones you will find today are tri- or quadband. This means that they have 3 or 4 of the voice bands. If it is a triband phone you want to purchase, make SURE it has the required spectrums, Cingular uses A TON of 850 MHz towers, something that T-Mobile doesn't. It will probably also have 1800 MHz which is great if you plan on using the phone in Europe or anywhere but North America (Canada and Mexico run on the same voice freqs as us). Alright, so, you found a phone, let's say, the Motorola RAZR V3. It came as a quadband phone that was unlocked. "Cool," you think, "all I need to do is pop my SIM in and I am ready to roll!" Not quite, tiger. Unlocked phones will work with basic services like voice calls and SMS (text messaging) out of the box. That's because all the proper settings are stored in your actual SIM card, not on the phone itself. Since this phone has not been programmed for use on any specific carrier, it is time to do a little tweaking. You will need to input settings for MMS (multimedia message service), the Internet Browser and voicemail. Luckily, the first two things can be accomplished simply by calling your provider and asking for an OTA (Over-the-air) update for MMS and internet to be sent to your handset. Voicemail is a bit trickier and involves doing a bit off scouring for your call center number, but it can be accomplished in as little as 5 minutes using Google. THE FOLLOWING REFERS TO CDMA TECH ONLY. CDMA is a little tricker since the only real market for it is in America, and since the biggest CDMA provider in America is also the greediest (Verizon Wireless), very few manufacturers really care about making cool phones for CDMA. The reasoning is because VZW likes to cripple its phones ability to use Bluetooth to transfer files and other things so it can charge its customers more to use its proprietary services. So, if you have Sprint or VZW, you really are limited to the phones they offer. Alternatively, you can buy a phone direct from the manufacturer (like Motorola or Nokia) and pray that VZW or Sprint will activate it. Changing numbers isn't as easy as with GSM either, since CDMA doesn't use a SIM based registery. Your phone contains a unique serial number, known as the ESN (Electronic Serial Number) for CDMA and IMEI (International Mobile Electronic Identifier) for GSM. In order to use your new phone with your existing number, you have to go online and tie your new ESN with your account number. If you can't do that, you need to go to a VZW or Sprint store and pay them $35 to do it for you. THE FOLLOWING REFERS TO iDEN TECH ONLY. You're fucked. No one gives a rats ass about iDEN except Moto and RIM (people who make Blackberry). You can look on eBay for a new phone, but the selections won't be anything worth looking at.