GSM
Cell Phone Unlocking FAQ
Information and answers
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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.
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.
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.
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.
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.
Why should I unlock my phone
There are three main reasons
why you might want to unlock your phone.
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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
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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.
Related Articles, etc
Originally published
15 Mar 2004, last update
21 Jul 2020
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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