There is an abundance of used cellular equipment available for purchase on eBay and elsewhere. For many people all the gizmos and gadgets are not necessary and all that's desired is "a phone that works". At the rate that the average person upgrades or replaces their cellular phone eBay provides an excellent opportunity for the consumer that may not be ready to or necessarly want to agree to another 1 or most of the time 2 year service contract with any particular wireless provider.
Unlike the rest of the world, the US providers provide equipment at a discount with the condition that you agree to pay your bill no matter how your service may degrade or any other issues that may arise out of this relationship. This subsidzed price is usually $150 or more off the retail price of that RAZR you have your eye on, so instead of paying $250 you in turn promise you will pay your bill and get it for let's say $49.99, (after the extra $50.00 mail in rebate). Now this $250.00 price isn't some inflated number that 'insert carrier name here' decided to throw out there. To purchase the same RAZR from Motorola it would cost you $250, like it would if you had cellular service in the UK for instance.
So what can you do?
That is easy purchase your own equipment and aviod the contract game. Some of you that have "been around the block" might remember a day and age where, if you had a telephone. (the kind that plug into the wall) unless that telephone was made by, purchased from and maintained by "Ma Bell" you could not plug it into said wall. Luckily that time has passed and we are older and wiser because of it.
Or are we??
Just because your cell phone bill says 'insert cell company name' does not mean you have to goto 'insert cell company name' to buy your cell phone. Well not quite.
In US there are 3 types of cell phone services or "frequencies" if that makes it any easier to understand. That are still in widespread use.

The 2 most widely used services are;
CDMA (code division multiple access) - The major carriers that use this type are Verizon and Sprint PCS. (as well a several smaller carriers)
Now don't jump ahead quite yet! When I say Sprint PCS, I mean Sprint PCS, not NEXTEL. Now I realize that the "New Sprint", "Sprint together with Nextel" is all one company this does not mean the two different "frequency's" are automatically going to be converged.
GSM (Global Systems for Mobile) - Cingular (The NEW AT&T), T-Mobile
and the 3rd is....
IDEN (Integrated Digital Enhanced Network) - Nextel

Among the 3 listed here there are several outdated technologys that see little usage anymore. Phones that utilize this type of technology are of little use if you plan on using it in any way. This includes phones that are built into cars and if you already have this type of phone and want to just replace you that may of been lost or broken. Most of the carriers refuse to activate these types of phones because it is far too costly to maintain the network.
The oldest widely used being-
AMPS (analog) - The definate day analog will be shut off is uncertian, but it will be in the next 2-5 years. If you are so lucky to still have a analog phone and it works, don't loose it. None of the carriers will allow you to change to another one. Doesn't matter what you say or do, it's not gonna happen. Just a note- You know all those call boxes along the highway, those are all analog boxes.
TDMA (Time Division Multiple Access) - TDMA is still used by quite a few prople and for the most part works well for making phone calls. However it still requires your carrier to change your phones unique serial number in their system inorder for it to work. You may still be able to change your TDMA phone if it is lost or broken but time is running out. The last company to offer TDMA was AT&T wireless. Not the company that is the new Cingular, the old AT&T wireless. (confused yet?) For the sake of argument we'll call the old AT&T wireless AWS. AWS offered TDMA up until the very end right before they became Cingular. Cingular however was very quick to get people off the TDMA network before and after AWS and are still doing so. Just a note- If you have a prepaid TDMA phone you won't be able to activate it as prepaid again if it is ever lost or broken. Cingular-(New ATT) was recently sewed by the company that made the system that billed all of it's prepaid TDMA calls. They have to pay a hefty premium for every minute that you use that phone. It actually costs them more than they are making for you to use the phone.
There are also a couple that are combinations of 2 seperate services.
For example GAIT, GAIT is a combination of TDMA and GSM. This was only used briefly, mostly for the transition from TDMA to GSM. In areas where GSM was not yet widely available.
And now PowerSource, the combination of IDEN and CDMA. Catch my drift?

How to Buy.
Electronics companies make cell phones not carriers. ( ie. Samsung, Motorola, LG, Nokia). But that does not mean if you have Sprint Motorola RAZR you can activate on your Verizon account.
All US companies for the most part try to restrict you from using another companies "branded" phone. (Back to the contract thing again) The 2 most difficult being Sprint and Verizon. These 2 may use an identical network being CDMA it is now all but impossible to activate a Sprint phone with Verizon or Verizon Phone with Sprint. At one point is was not a problem but they are now very quick at verifying if this is and always has been branded from one particular company and I have heard of little success lately. So if you have Verizon and want to keep them you have to get another Verizon branded phone, or if it is Sprint or Virgin Mobile, etc. etc. it is the same.
It is a little easier with the other 2 or any company in the US that uses GSM. One way to verify if your phone is GSM or CDMA is to take off the back and look for a SIM card (Subscriber Identity Module) NOW WAIT!!! Nextel also uses a SIM card but Nextel only works with Nextel. You can't take your SIM card out of a Cingular phone and put it in Nextel. NO MATTER WHAT! It won't work the other way either.
That being said, the way it will work is if your phone has a SIM card and it is from a US carrier and it is not NEXTEL you can use it in most any other GSM phone. The important factor being a US carrier. Reason is most companies out of the US use GSM but the primary frequency of the GSM abroad is completely different. With some exception and I will explain later.
Now you have your Cingular SIM and just bought a T-Mobile phone. You can just pop in the SIM and be ready and making calls, right? Not quite. GSM companies are not quite that giving. If you try to take your Cingular SIM and put it another phone that is not branded Cingular, meaning when you turn it on it says Cingular on the screen, most likely it will be subsity locked. Meaning you will need that particular "subsity code" to be able to use it and make calls or anything for that matter. Fortunately on eBay there are alot of great folks who sell unlocked GSM phones and some that you pay to unlock them for you. Some phones are easier to unlock than others, it is best to ask before you buy just to be sure.
Ok, your phone is unlocked. You're calling all your friends and telling them how great it is to be using your new Sidekick 3 with Cingular. But wait! Chances are that you still won't be able to send pictures or get on the web. Now it is possible to fix this too and I will try to explain at a later time.

Hope I've been able to answer some of the more common questions regarding this type of purchase and hopefully it will help you make a more informed decision when deciding to purchase your next new or used cell phone.

Guide to safely and easily buying a used cell phone. v1.0 3-23-07 Michellem2289