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Your GSM cell phone is designed to be used with any service provider's SIM.

But the chances are that your service provider has locked your phone, restricting it and you to only use their service.

But there is nothing to prevent you unlocking your own phone if you wish to.

 
 
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GSM Cell Phone Unlocking FAQ

Information and answers
 

 

Here's how to unlock the full potential of your GSM cell phone so that it can be used with any service provider, anywhere in the world.

With an unlocked phone, you simply plug in a different SIM card (the small bit inside these larger credit card sized holders) to change service providers.  Simple, easy, and instantaneous.

 

 

Our unlocking service has been positively written up in the Washington Post, the Philadelphia Inquirer, other newspaper articles, featured on CNN, and on many websites.

In recognition of the huge number of visitors to our unlocking pages we're now getting every day, here are answers to some of the questions more commonly asked.

And, if there's a question that we've not answered, please let us know so we can add your question (and our answer) to this list.

Contents

What is a SIM and what is unlocking 

What is GSM?  Is it different than normal cell phone service?  How do I know if I have GSM or not? 

Will my existing cell phone service provider know if I unlock my mobile phone 

Will my existing service provider care if I unlock my phone 

Is it legal to unlock my phone 

Can my existing service provider relock my phone without telling me 

How do I know if my phone is already unlocked or not 

How do I know if my phone can be unlocked 

Which companies have GSM in the USA? 

I don't have a GSM phone, but will be traveling internationally so need one.  Can I just buy an unlocked phone without signing up for service? 

How do I unlock my phone 

How do I know that my phone has been successfully unlocked 

I've unlocked my phone, but when I turn it on, it still shows the name of the previous wireless service 

How do I know if my phone will work internationally 

Which countries will my unlocked phone work in 

How/where can I get a SIM that will work internationally 

Do I need any credit checks or anything to get a foreign SIM 

Is there any sort of minimum contract I have to sign for a foreign prepaid SIM 

Why should I get a different SIM for traveling internationally 

Will I have to unlock my phone every time I change SIMs 

Will my existing service still work with my unlocked phone 

Will I be able to get better reception and roam more in the US with an unlocked phone 

Will I save money with an unlocked phone 

How do I get my phone unlocked 

Why should I unlock my phone 

Other Questions? 

 

FAQs (Frequently Asked Questions)

What is a SIM and what is unlocking

Ordinary cell phone service works so that the unique serial number in your phone (its 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 your phone and knows to send phone calls to that phone when someone dials your phone number.

A GSM phone is not directly linked to you.  Instead, it has a removable account card, called a SIM (subscriber information module) and this SIM has a unique serial number on it.  This is what identifies you to the wireless provider.

The important difference about this is that you can put your SIM into any compatible phone (and pretty much all modern GSM phones are compatible with all modern SIMs) and that phone will now act as your phone, because the wireless company sees your SIM inside it.  It doesn't care that you've changed phones, all it cares is where to find your SIM.

And now for the really exciting part of this.  Just as, in theory, you can put any SIM in any phone, the opposite is also true.  Any phone can work with any SIM.  So, if you've already bought an expensive phone that you like and have learned how to use, if you change from one GSM wireless company to another one, you don't have to change phones.  You can keep the phone you've grown to like, and all you need to do is replace the first company's SIM with your new service provider's SIM.

But, some wireless providers 'lock' their phones, meaning that their phones have been programmed to only work with SIMs issued by their company.  Reversing that programming - unlocking your phone so it can work with any SIM - is what this is all about.

What is GSM?  Is it different than normal cell phone service?  How do I know if I have GSM or not?

GSM is a type of digital mobile phone service.  The more common type of digital mobile phone service in the US is CDMA, but just about every other country in the world uses primarily or only GSM.

For you as the user of your phone, there is no difference at all between using a phone on a CDMA system or a phone on a GSM system.  Unfortunately, the two different systems are not compatible with each other.

If you have a T-Mobile, Cingular, or recent new M-mode type service with AT&T, then you have GSM service.

Will my existing cell phone service provider know if I unlock my mobile phone

We're not sure about this.  Certainly, if they physically have your phone, they can get it to display its current lock status, but when you have the phone, we're not sure.  It might be possible, in theory, for them to interrogate the phone through the cell service control signals, and get the phone to advise of its status, but we've never heard of this being done.

And, in any case, read the next two questions/answers for further reassurance on this topic.

Will my existing service provider care if I unlock my phone

Probably not!  That is one of the ridiculous things about unlocking which makes the whole thing so unnecessary.

You have already signed a one or two year contract with your cell phone service provider, you are committed to spending a monthly minimum amount with them every month, whether you ever turn your phone on or not!  Indeed, in a way, it is probably good for them if you never use the free minutes included in your plan - that way, their monthly fee becomes pure profit!

So, why should they care if your phone is locked or unlocked?  Apart from hoping you'll use more than your free minutes, it is all the same to them, one way or the other.

Is it legal to unlock my phone

It is your phone, isn't it?  Then surely it is as legal that you unlock your phone as it is that you give it away, lose it, break it, leave it turned off, or do just about anything else with it!

Unless your phone service contract says 'this phone remains the property of us (the service provider) and you agree not to modify or alter it in any way' then there would seem to be no reason why you can't legally do anything you like with your phone, just so long as you're not attempting to defraud anyone.

It is illegal, in some countries, to change the phone's IMEI (serial number) - this is a type of what is called 'cloning' and, particularly with non-GSM phones, could enable you to then pretend to be someone else and have your airtime charged to someone else's account.

We don't provide any cloning type service and don't approve of people that do.  But we do help you simply unlock a phone that belongs to you so you have freedom of choice as to which service provider you use it with.

Can my existing service provider relock my phone without telling me

We used to think the answer to this was 'no, of course not'!  But then a reader wrote in to tell us how he bought a Treo, new and unlocked, and after using it with T-Mobile, changed his service provider and started using it with AT&T.  To his surprise and horror, AT&T somehow then locked his Treo and now are refusing to unlock it, even though he never bought it from AT&T and never let them touch it.

Somehow they apparently sent a locking signal to the Treo that locked it to their SIM.  This understandably upset the owner of the Treo.  It was 100% his Treo - he'd paid full price for it, buying it from a regular store, not from a cell phone service provider, and then signed up for an account with AT&T that had no special incentives associated with it.

So, maybe it is indeed possible for your phone to be relocked.  So keep your unlocking codes in case you need to use them again!

How do I know if my phone is already unlocked or not

Easy.  Borrow a SIM from a friend who has an account with a different wireless service provider and see if it works in your phone or not.  If it works, and your phone thinks it is his (or her) phone with that phone's number, then your phone is already unlocked.

But if it creates some sort of error message and doesn't work, then your phone is locked.

How do I know if my phone can be unlocked

As far as we are aware, all GSM phones can be unlocked.  But if your phone is not a GSM phone, then it probably can't be unlocked; indeed, the whole idea of locking/unlocking phones doesn't really apply to non GSM phones, because your phone number and account is tied to your phone, not to the movable/replaceable SIM chip that is inside it.

Which companies have GSM in the USA?

There are two main companies that offer GSM service in the USA.  AT&T and Cingular are now merged into one company, and the second company is T-Mobile.

If your service is with, eg, Sprint, Nextel, Verizon, or just about any other US wireless company, then you do not have GSM service and your phone can't be unlocked.

I don't have a GSM phone, but will be traveling internationally so need one.  Can I just buy an unlocked phone without signing up for service?

Yes, there are several ways to buy an unlocked phone without needing to sign up for a year or two of service that you mightn't need.  You can simply buy a used GSM phone on eBay or somewhere like that, but this is not without potential problems inherent in buying any used electronic equipment.

If you do buy a used phone this way, check to confirm it truly is unlocked (to be kind to sellers, many sellers don't understand exactly what locking is and so incorrectly describe their phones as unlocked) and check it will support the frequency bands used in the countries you're likely to visit.  Also consider buying a new battery, because batteries do wear out.

You can also buy new unlocked phones.  Telestial have a broad range of new unlocked phones.  And, ahem, we now sell the very nice tri-band Motorola V66 ourselves, too.

How do I unlock my phone

There are two ways that a phone can be unlocked.

If you are lucky, you have a phone that can be unlocked simply by keying a secret code into it.  The code is usually a unique number only for that particular phone, based on its serial number (what is called its IMEI) and the service provider who locked it.  We can sell you this secret code for most models of Nokia phones and some other types of phones, too.  It costs only $5 and is easy for you to enter into your phone.

Other types of phone need their 'firmware' - their operating system software - to be rewritten to remove the lock.  This requires connecting the phone via a special data cable to a special programming unit.  We provide this service for various models of Motorola, Siemens, and Sony Ericsson phones, plus the Treo 600 phone/PDA.

How do I know that my phone has been successfully unlocked

Usually, after entering the unlock codes, the phone will say something that sounds sort of encouraging.

Do the test in the question two above.  Borrow a SIM from a friend who has an account with a different wireless service provider and see if it works in your phone or not.  If it works, then your phone is already unlocked, but if it creates some sort of error message and doesn't work, then your phone is still locked.

I've unlocked my phone, but when I turn it on, it still shows the name of the previous wireless service

This logo (called a 'splash screen') has been programmed into your phone by the company that sold it to you.  It doesn't mean anything about which company now provides you phone service.

Unlocking your phone removes the electronic restriction that prevents your phone from working with other SIMs from other wireless services.  It doesn't change your splash screen.

The good news is you can get rid of the splash screen without needing to unlock your phone.  See if you can find in your phone's manual how to change the splash screen, or consider calling the phone manufacturer and have them walk you through it.

Which countries will my unlocked phone work in

(See the next question as well).

GSM service is offered in 207 countries.

Check this website to see if the country you are interested in has GSM service, and, if it does, what frequency the GSM service(s) operate on.

How do I know if my phone will work internationally

US GSM cell phones work on 1900 MHz (and sometimes also 850 MHz).  Most other countries have GSM networks on 900 or 1800 MHz.

Check on the website of your cell phone manufacturer to see which frequencies your model phone supports.  Here are sites for the most common phones (let me know if your phone isn't included, and I'll then add it to the list) :

How/where can I get a SIM that will work internationally

Well, the easiest way to get a SIM that works in a foreign country is in the foreign country itself!

But, oftentimes, this is actually not the easiest way to get a foreign SIM.  When you're traveling, you don't want to have to find a cell phone store, and try and sort out what you need, perhaps in a different language, and potentially have things go wrong.

For this reason, many people choose to buy a pre-paid SIM for the country or countries they'll be traveling to before they leave home.  Several companies will sell them to you; we recommend Telestial because we've dealt with them ourselves, we know them, and find them helpful, honest, responsive and reliable.  They have a wide range of SIMs and fair prices.

If you buy the SIM before you leave, you have a chance to make sure you understand how it works, and will also know its phone number, which you can then conveniently give to people so they know how to contact you.

Do I need any credit checks or anything to get a foreign SIM

Probably not.  Most people buy a SIM that works on a prepaid type account basis.  That means you pay money into your phone account, and then use it up as you make calls.  When it is used up, the account stops working until you pay more money into the account again (either by credit card over the phone, or by purchasing a 'top-up' card that transfers money into your phone account.

Because the wireless service provider isn't extending you any credit, you don't need to pass any credit checks, and you don't need to have any sort of proof of fixed address in the foreign country or anything.  Most of the time you just buy the prepaid account and SIM without any need for any paperwork at all, put the SIM in the phone, perhaps dial a number to activate it, and it is instantly then working.

Is there any sort of minimum contract I have to sign for a foreign prepaid SIM

No.  Because the wireless service provider isn't giving you a free phone or any other sort of subsidy, you don't have to commit to a one or two year term.  You just buy the SIM, use it as much or as little as you like, and stop using it whenever you choose.

Why should I get a different SIM for traveling internationally

You should read our four part series on international cell phone service.  This explains all the different issues and options you have as to how best to keep in contact when traveling out of your home country.

Will I have to unlock my phone every time I change SIMs

No.  Once your phone is unlocked, it remains permanently unlocked, no matter what you do to it, unless you specially program back the lock code into it.

Will my existing service still work with my unlocked phone

Yes, your existing service will work perfectly with no change, as long as you leave your present SIM in your phone.

Will I be able to get better reception and roam more in the US with an unlocked phone

No.  Unlocking does not make any difference to how your phone works with its present wireless service provider.  It still uses the same transmitters on the same towers as before, and does everything the same.  The only difference is that you can take its SIM out and replace it with a different SIM for a different wireless company.

Will I save money with an unlocked phone

Maybe.  Your current wireless provider will still charge you exactly the same as before for all your calls.

But because your phone is now unlocked, you can use a different SIM from a different provider whenever this might give you better rates - for example, when traveling overseas.

How do I get my phone unlocked

If you have a Nokia or selected other phones, then we can unlock it for you remotely.  Simply go to our GSM unlock page, fill out the form, pay the $5 fee, and we'll send you back your phone's unlock code and complete instructions on how to unlock it.

If you have a Motorola, Siemens, or Sony Ericsson phones, plus the Treo 600 phone/PDA then we can probably unlock that phone too, but you'll need to send the phone to us for unlocking.

If your phone is not on our current list of phones we can unlock, ask us and maybe we can now unlock it, too.

Why should I unlock my phone

There are three main reasons why you might want to unlock your phone.

  • Because you want to change the wireless company you get service from in the US, and want to keep your present phone.

  • You've changed to a different service provider and got a new phone, but you want to unlock your old phone so you can use it in an emergency just by swapping the SIM over if your main phone gives problems

  • Because you want to travel internationally and don't want to have to pay the very expensive international rates your present wireless company would charge you while internationally roaming.

Other Questions?

If there's another question you'd like to ask, please do so.  We're pleased to help.

 

 

Originally published 15 Mar 2004, last update 08 Jul 2017

You may freely reproduce or distribute this article for noncommercial purposes as long as you give credit to me as original writer.

 
 
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