Still, many people do not know what unlocked cellular phone models are and how to use them if they have them. Let's take a look at some of the most basic questions and their answers surrounding these phones.

What is an unlocked cellular phone?
These phones are simply models that can be programmed to accept different service provider information. This means a phone purchased to work with one plan can be transferred to another with a few basic programming steps.

Can any cell phone do this?
No. Phones that have the portability and freedom options of unlocked service are only GMS models. These are special phones that can handle information changes.

Where are these phones found?
GMS phones are typically those sold by such service providers as AT&T, Cingular and T-Mobile. They can also be found through other companies, but it pays to ask. These phones can also be found in cell phone retailers and online.

How do they work?
Unlocked cellular phone service works by switching out SIM information in the phone itself. The SIM, or subscriber information module, has the user's information, the serial number of the phone and calling information. When a phone is turned on by a company, this SIM is programmed with information to allow it to work with that service. There are simple steps, generally, anyone can take to find their SIM information.

How do you unlock a SIM?
To make one of these phones compatible with another service, the SIM needs to be unlocked, thus the name. This process is generally achieved using a special programming code. These codes are sometimes sold with the phone, or the phone will come unlocked so it can be programmed at will. There are locations that help cell phone owners find the right code, too. Some cell phone service providers will help with this, as well.

Is this legal?
Technically, yes. When an unlocked cellular phone is purchased by a buyer, that phone is theirs. It does not belong to the service provider who sold it. Some cell phone companies do, however, make it very difficult for people to use the phones they sell with other services. Others are not quite as proprietary.

What is the benefit of this type of phone?
These models give their owners more freedom. When an expensive cell phone, that happens to be one that can be unlocked, is purchased, the investment can carry through to different service providers and plans. These phones also take away the worry of having to reprogram a new phone with numbers and other important information. Many people refuse to use anything else, especially when more expensive cell phones are purchased.

The unlocked cellular phone option isn't a new one, but it's one that is really catching on. As phones become more complex and expensive, having the option for portability is something many people insist on.