A cellular phone that uses the Global System for Mobile () network and can access multiple cellular phone networks is called an unlocked. A locked cell phone is sold by the cell phone service provider and cannot be used with any other provider. In many places, including the US, each service provider locks the phones they sell to restrict their transferability and to require consumers to purchase a new phone when switching service providers. Iphone 4s Unlocked For Sale No Contract there. Unlocked GSM phones can be purchased from stores that are not affiliated with a specific cellular phone service provider.

An unlocked GSM phone is a cellphone that uses a GSM network and can access multiple cellphone service provider networks without.

These phones typically cost more than the locked phones, as the cost usually is discounted by the service provider. In many cases, the longer the, the larger the discount available on the phone itself. The is a digital signal network used in more than 212 countries and territories around the world. Although all GSM cell phone users can access the network to make and receive calls, they are charged additional access or roaming fees by their cellular provider for activity using another companies network. Having an allows customers to take advantage of the network as they and pay only the local cell phone usage fees.

Due to the digital format of the GSM network, the development of short message service (), or text messaging, was possible. The worldwide emergency phone number 112 was also developed due to the expansion of the GSM network to allow international travelers to quickly locate emergency services when needed. Further enhancements to this network increase the strength of the signal in remote areas and further decreases the costs to the service providers. Unlocking a GSM phone requires changes to the software settings on the phone to allow the use of a subscriber identity module (SIM) card from other service providers. The phone number of the cell phone and the information required to connect the phone to a cellular service providers network is stored on the, a small device the size of a post office stamp that is usually located under the battery of the cell phone. Consumers can purchase an unlocked GSM phone and then purchase a SIM card from the service provider he or she wants to use.

People who are traveling in the US, Europe, or Asia can often purchase the SIM cards directly from the cell phone service providers on a pay-per-use service plan. They may need to purchase multiple cards if they plan to travel widely, so that they are not charged roaming fees. To access the cell phone services, the person can take his unlocked phone, insert the SIM card for the local service provider, and turn on the phone. He is now able to make and receive phone calls and text messages using the SIM card service provider network. The user should take note of the phone number for the SIM card installed, as it will be displayed when he powers on the phone. I'm shopping for a new Samsung Galaxy Note 4 (everything's bigger).

Some are listed as 'new', but say they're 'good as new factory replacements'. Others say they're new but have been opened for unlocking.

Some say simply 'unlocked' while a few say 'factory unlocked'. Your article seems to suggest that the device must be opened to be unlocked (removal or replacement of the SIM card), but how can I be sure the 'new' phone I buy isn't really a replacement or refurbished unit? Are sellers required to tell me? I have the same question as anon57124. I also got my AT&T phone unlocked by the service provider and started using another network, but I am not able to do browsing or web services.

In my case, I can use the phone for calls and text only. I am only able to use the phone for calls.

The new cell provider downloaded a program that entered their network URL and other info into the browser preferences list, but when I try to access the web, only the service provider's homepage connect is activated.