What is an Unlocked GSM Phone?

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  • Written By: Carol Francois
  • Edited By: Bronwyn Harris
  • Last Modified Date: 21 September 2019
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A cellular phone that uses the Global System for Mobile (GSM) network and can access multiple cellular phone service provider networks is called an unlocked GSM phone. 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.

Unlocked GSM phones can be purchased from stores that are not affiliated with a specific cellular phone service provider. 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 service contract, the larger the discount available on the phone itself.

The GSM network 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 service plan provider for activity using another companies network. Having an unlocked phone allows customers to take advantage of the network as they travel the world and pay only the local cell phone usage fees.


Due to the digital format of the GSM network, the development of short message service (SMS), 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 SIM card, 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.


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Discuss this Article

Post 21

How do I tell if my note 3 is a gsm phone and can I use it with consumer cellular?

Post 20

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?

Post 16

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. Please help. 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.

Post 15

You can unlock any GSM phone to be used on any GSM network very easily. I actually unlocked my blackberry very easily. It took only 10 minutes to unlock my phone. I got the unlock code very cheap online. They sent me my unlock code very quickly and I unlocked my phone within a couple minutes. Hope I helped you guys. Cheers!

Post 13

we have pre-paid cell phones through verizon, but they don't have a sim card. what do we do and does this GSM work for pre-paid?

Post 12

how do I convert my samsung cdma to gsm?

Post 11

I 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. I am only able to use the phone for calls. Please help.

Post 10

i have an o2 sim card. can i use it in GSM unlocked phone?

Post 9

Is there a phone that uses both CDMA and GSM?

Post 8

Can my Motorola Clutch i465 phone be unlocked from Boost Mobile, to be uesd by other providers, or will it stil have to be connected to sprint nextel service, being a push to talk phone? I don't really need the push to talk feature. thanks

Post 7

can the HTC Pro be unlocked to be used on the t-mobile network?

Post 5

how can I unlock my LG 600G

Post 4

Hi Jerry,

Remember, Sprint and Nextel are the service providers, not the phone manufacturers. If you like a particular phone, find out who is the actual designer. It should be a technology firm, such as Samsung, LG. You can then contact these firms and ask where you can purchase an unlocked phone.

I hope this helps.

Post 3

Where can I buy Sprint or Nextel cellphones directly from the manufacturers?



Post 2

Most GSM phones can be unlocked with the use of specially designed 'unlocking' software. These products are widely available on the Internet.

Post 1

how do i unlock a gsm phone?

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