When searching for cell phones on eBay or the internet at large, you may have run across the term unlocked cellular phone. What does that mean? If a cell phone is locked, that means that it can only be used with one cell phone carrier company. For example if the cell phone was locked by AT&T, it can only be used with AT&T and not T Mobile or another carrier.

Wireless carriers started requesting that the manufacturers lock their cell phones a few years ago. This all came about when cellular service carriers started offering free or deeply discounted cell phones if you signed up for a one or two year contract. The wireless carriers still do this now. To keep someone from signing up, getting the free phone and then switching to a different carrier, the wireless carrier companies had their phones locked by the manufacturer. This lock is also called a sub lock, spc lock or sim lock.

How can you tell if you have an unlocked cellular phone? First you must determine if your cell phone is GSM or CDMA. If your cell phone uses a sim card then it is GSM. U.S. GSM carriers are Cingular and T Mobile, for example. CDMA carriers are Verizon Wireless, US Cellular, Alltel, Qwest and Sprint PCS. Both types of cell phone can be locked and unlocked, but only the GSM phones can be easily switched from carrier to carrier.

The GSM cell phone is the easiest to deal with as once its unlocked, the unlocked cellular phone will work with any active sim card. This means that you could insert an active T Mobile or Cingular sim card into the phone and it will work and make a call. You may not be able to browse the web on that phone though if the phone is not programmed to that carrier.

CDMA cell phones do not use sim cards and therefore must be programmed to work with another carrier. If you do not have the special software to do this, then its not possible to unlock the phone. CDMA phones are pretty much locked to the carrier they were made for.

If you want an unlocked cellular phone, you can buy on one on eBay already unlocked. Or you can find a company on eBay or the internet that does business unlocking cell phones. Some of these companies can unlock the cell phone remotely too.

For more unlocked cellular phone information, visit http://www.cellphonesinfosite.com, the #1 website specializing in providing news, advice, tips and the latest resources on cellular phones.