Unlocked Mobile Cell Phones

Today unlocked used cell phones are the choice of many people because they allow you to use the cell phone of your choice with the carrier you prefer to use not the one who forces you to sign a contract. Nobody likes to be forced to use one company over another which is why these remain such sought after cell phones.

GSM mobile cell phones are designed to be used with a Subscriber Identification Module (SIM) card. A SIM card is a microchip that stores the subscriber’s data.

The original SIM card is issued by the carrier and enables cell service by actually activating any phone into which it is inserted. Unlocked cell phones allow you to use the network of your choice in most parts of the world. The transition from one area relies on the phones ability to switch frequencies when necessary in a highly transparent fashion. Are there unlocked used iPhones for sale today? Yes. If you want to use a smartphone like the iPhone 3G and 3GS then you can enjoy the benefits of unlocked iPhones.

Part of what SIM cards do is store network specific information which is used by the carrier to authenticate and identify a subscriber on the network. This information is just one example of the use of wireless technology relying on its own power to provide reliable authenticated communications.

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In the case where a phone is locked, it will only recognize a SIM card from a single issuing carrier. If a cell phone happens to be unlocked, it will then recognize a SIM card from any carrier.

The actual locking of a phone is done through software settings embedded into the chips within the cell phone. This keeps the carriers happy because it keeps the customer so called loyal to the carrier.

Unlocked cell phones let you get around this situation in a completely legal manner. In November of 2006, the United Stated Copyright Office issued a statement that you have a right to unlock your cell phone. Basically you can go with who you already like or checkout other companies to see if they provide service which better suits you. Cell phone plans differ widely offering plans tailored to fit the needs of individuals from all walks of life and all budgets as well. Plans from various providers have become increasingly more competitive and many of the plans are considered to be the best value because the phone is usually included either free or at a substantial discount.

GSM cell phones come with the ability to use multiple bands so that they will work in more than just one country. The fact that there is not just one universally transmitted frequency means that the technology by design allows maximum versatility around the globe.

Originally, the wireless carriers such as AT&T and others began a marketing strategy where they would pay for some of, or even all of, the cost of a new cell phone. This would occur only if the customer agreed to commit to a one or two year contract agreeing to use the particular carrier’s wireless service.

Carrier provider’s cell phone service plans work in a way that uses the unique serial number in your phone, the ESN. The ESN is used by the cell phone service provider to identify who you are. The wireless service knows that a particular phone’s serial number is really your phone and also knows to send phone calls to that phone when someone happens to dial your particular phone number. Smart technologies for smart people on the go who need to stay in touch find the ability to shop around for the right network provider to be number one benefit of an unlocked cell phone. This has had a positive result in the marketplace over the last few years as providers continue to become more competitive in their prices and plans.

The Electronic Serial Number, or ESN, is a unique identification number which is assigned to each and every cellular phone during the manufacturing process and is done for security purposes. The ESN identifies a particular phone to the cellular system whenever you make or receive calls. During this process, the phone will be validated by the Mobile Telephone Switching Office or MTSO with every call.

The makeup of the ESN, which is a 32-bit number, is designed in three parts which include the manufacturer code, a special reserved area and the manufacturer assigned serial number.

Keep in mind that in November of 2006, the United Stated Copyright Office issued a statement that you have a right to unlock your cell phone.

On the more entry level side of the multiple band GSM technology is the dual band phone which works with two GSM frequencies. This type of cheap unlocked cell phones are typically less expensive than others and still offers the ability to send text SMS, MMS, and provide WAP capabilities as well.

Unlocked GSM cell phones which run on three frequencies are referred to as tri-band phones and are basically the next step up from dual band technology and is still cheaper than the quad band.

The quad band unlocked cell phone which is often referred to as an international phone is the way to go if you travel a lot because these can be used anywhere world wide. These are worth the extra money for many people just due to the fact that they are known for providing a much broader range of functionality and less instances of not getting good reception.