A Cell Phone uses a unique serial number in your
phone known as its ESN.
The ESN is used by the cell phone service provider to identify who
The wireless service assigns your phone's serial number to
correspond with your phone number, and knows to send phone calls to
that phone when someone dials your phone number. A GSM (Global
System for Mobile communications) phone is not
directly linked to you. It has a removable account card, called a
SIM (subscriber information module) and this SIM has a unique serial
number on it.
This unique serial number is what identifies you to
the wireless provider.
A SIM card stores
The SIM card is issued by a carrier and provides cell service by
activating any phone into which it is inserted.
If you've already
bought an expensive phone and you change from one GSM wireless
company to another, you don't have to change phones.
You can keep your phone, and all you need to do is replace the first
company's SIM with your new service provider's SIM.
is that some wireless
providers lock their phones.
This means that their phones have been
programmed to only work with SIMs issued by their company.
Reversing that programming is called unlocking the phone.
You unlock a phone so it can work with any SIM.
A locked phone, will only recognize a SIM card from a particular
If the cell phone is unlocked, it will recognize a SIM card from any
The "lock" is a software setting that keeps the cell phone "loyal"
to one carrier.
In areas like the United States, where carriers offer free, or
deeply discounted phones with cell plans, the phones are commonly
locked so that they wont work with other carriers.
Carriers claim this is necessary to subsidize the cost of the
After a period of time, a carrier might agree to unlock the phone
upon request, possibly charging a fee.
Due to proprietary settings sometimes installed in locked handsets,
the phones wont always function correctly with other carriers, even
once unlocked. This usually applies to carrier specific special
features for your phone, which are programmed in to the phone. They
may not function.
From the consumer viewpoint, the practice of carriers locking phones
and using proprietary settings defeats many of the benefits of SIM
Complaints led to a class action suit. Phones should be left
unlocked, or at least unlocked after the initial contract expires.
You can get an unlocked phone without proprietary settings if you
buy it new from a third party vendor in its original, unlocked
The downside is that the price is usually close to full
retail. Some consumers might not want to pay big money for a
phone they can get for free with a plan. The advantage of
the third party unlocked phone is that it should work equally well with any
carrier that uses SIM cards.
Third party services will unlock your cell phone for a fee. This
doesn't guarantee the unlocked phone will work correctly, as
unlocking it doesn't change any carrier specific proprietary
settings your phone may have.
There are hacking instructions online to unlock many phones, but a
phone that is unlocked improperly can end up non-functional.
Carriers operating on the GSM network use SIM cards.
In the United Sates, this includes Cingular Wireless, which merged
with AT&T Wireless, and T-Mobile.
Carriers that use the competing CDMA (Code Division Multiple Access) network don't use card-enabled
These carriers include Sprint PCS, Verizon and Virgin Mobile.
The CDMA equivalent of the SIM card is the R-UIM which will be used
by carriers in the future.
R-UIM cards are already in use in some parts of Asia.
There are three reasons why you might want to unlock your phone:
1. Because you want to change the wireless company you get service
from in the US, and want to keep your present phone.
2. You've changed to a different service provider and got a new
phone, and you want to unlock your old phone, so it can be use in
case of an emergency, by swapping the SIM if your new phone ever has
3. Because you want to travel internationally, and don't want to
have to pay expensive international rates your wireless company
would charge you for international roaming.
traveling internationally, GSM service is offered in 207 countries.
US GSM cell phones work at 1900 MHz and some at 850 MHz.
Most other countries have GSM networks at 900MHz or 1800 MHz.
Check on the website of your cell phone manufacturer and see what
frequencies your model of phone supports.
In November of 2006 it became Legal to Unlock Cell Phones.
the United States an exemption that took effect 27 November 2006
which specifically permits unlocking your phone, and will expire in
three years 27 November 2009, but can be renewed after that.
The exemption only
applies to the actual unlocking, not to providing an unlocking
device or service.
How to Un-Lock your Cell Phone
are two ways that a phone can be unlocked, which way is used, is dependant upon
the phone being unlocked.
Your existing service will work perfectly with your unlocked phone.
If you have a phone that can be unlocked by keying a code into it you are
The code is usually a unique number for that particular phone, based on its
serial number or IMEI (International Mobile Equipment Identity) and the service provider who locked it. Enter *#06# into your phone to retrieve the unique 15 digit IMEI number. It can
also be found printed on the back of the phone underneath the battery.
Extracting MCC and MNC codes from your IMSI
The first 3 digits of the IMSI are MCC "mobil Country Code" code and next 3
digits are MNC "Mobil Network Code".
The confusion comes from some countries having a 2 digit network code and others
having a 3 digit Code (USA). For this reason, most major US carriers have MNCs
ending in 0, so that they are uniquely identified by the first two digits,
thereby providing their subscribers with compatibility on international
Take this sample IMEI number for example 404450014863533, here MNC code can be
45 or 450.
The Mobil Country Code is 404 (the first 3 digits), and the Mobil Network Code
can be either 45 or 450 (the next 2 to3 digits).
Before trying anything else, contact your service
provider and ask for an unlock code! (This IS the Best way to unlock your Phone)
Usually, if you've been a customer of theirs for some time, they will provide
you with an unlock code for free. You can not get a better price.
This is, by far, the best way to get your phone unlocked. If your Phone unlocks
with a code, in most cases your service provider will provide it, by just asking
for it. It is a common request for people traveling over seas. Many will email
you with the code and instructions for you to unlock your phone.
entering the unlock codes, the phone will say something like "SIM is not
restricted" or "Restriction off" or something encouraging.
Sample Procedure for unlocking a GSM Phone:
Get your IMEI, MCC/MNC numbers with the procedures above.
Get your phones
unlock code using the phones IMEI and Manufacturer data and Current Network.
Slide your phones SIM card out.
Put the battery back in and power the phone on.
You will see a message "Insert SIM Card".
Enter all of the characters you see in your unlock code, including the # symbols.
To get a 'p' press * 3 times, to get a '+' press the * key 2 times, to get a 'w'
press the * key 4 times.
Disregard any spaces in the code.
In order to unlock your phone you generally need to enter only one code.
Start with the first one.
If your phone is not unlocked by typing the first code, try entering another
(MCC (Mobil Country Code) + MNC
(Mobil Network Code) GSM phones), use code "7" (Multilock - CDMA
Once you have finished entering a code that works you should see a message that
says something like "SIM is not restricted" or "Restriction off" message
depending on your model. Phone unlock messages will vary, and the phone messages
can relate to SIM lock or Network lock, unlock messages.
If you don't get one of these unlock messages, indicating the unlock was
successful, try entering another code.
Message "Cannot undo restrictions" means the phone is "hard-locked" and cannot
be unlocked by code.
Attempting to unlock your phone is done at your own risk.
Most phones only allow you to try a certain number of unlock tries, Nokia phones
have a limit of 5 tries.
After that, the phone becomes "hard-locked", meaning it cannot be unlocked
without using special equipment.
Although it is legal to unlock your phone, your cellular
provider may choose to void your warranty.
Most of the newer phones will not work with the codes generated by the free
You can download unlock programs / software to generate the unlocking code.
Software is available on some websites for free and some pay websites that also
offer support if things go wrong.
Using software, if you have downloaded it, enter in your Manufacturer and Serial
Number (IMEI number) and generate your code.
Here are some web sites, and
download that generate unlock codes for a number of phones for free.
They could be worth a quick look:
Other types of phones need their "firmware" (operating system software) to be
rewritten to remove the lock.
This requires connecting the phone via a data cable to computerized equipment or
a computer and flashing /
Phones may be unlocked by updating the phone's
Unlocking applies to all cellular phones.
The steps provided above work for GSM phones.
You CANNOT use the steps above to unlock a CDMA or TDMA phones.
To "unlock" a CDMA or TDMA phones is known as reprogramming the phone.
For CDMA phones, you need the MSL (Master Subsidiary Lock), which you MAY be
able to get from your service provider.
Please note that you may not be able to get the MSL from your service provider,
as it usually is against company policy to give these to customers.
Switch off the phone. Hold the keys "3", "*" and "Call" and switch the phone on.
Keep the buttons held down till you see the word "Formatting..." on the screen.
Make sure that the battery is full charged before you attempt this. This should
reset the phone lock code.
Also some software is able to unlock CDMA, GSM and other phones to different
networks but you must watch out for the frauds.
After unlocking, the phone will 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.
For an unlocked phone it doesn't mean anything regarding which company is now
providing you with phone service.
Unlocking your phone removes the electronic
restriction that prevents your phone from working with SIMs from other
wireless service providers. It doesn't change your splash screen. You can
usually get rid of the splash screen. Doing so does not require you to unlock
your phone. Look in your phone's manual for how to change the splash screen, or
consider calling the phone manufacturer and having them walk you through it.
Unlocking for Free in the
The two national GSM carriers in the United States:
unlock your handset if you have an active account in good standing for at least
T-Mobile will also unlock a phone if you pay full retail price and
show proof of purchase through a faxed document.
AT&T Wireless, the other GSM carrier, will usually do so after 90 days, or once you have concluded your
contract, and may unlock the phone in some other situations as well.
Verizon Wireless, owned by Verizon Communications and Vodafone, have long
provided an unlocking code to customers who knew to ask for it.
Verizon Wireless and Sprint Nextel had several cases against them which resulted in settlements
requiring both companies to inform subscribers that the carriers will help
unlock phones when their contract ends.
are not compelled to unlock phones by any law or regulation, and they
may choose not to unlock certain phones.
AT&T, for example, has stated that they
will not unlock the iPhones under any circumstances, even after customers are
out of contract.
In a 2006 submission to the US Library of Congress' Copyright Office with
respect to DMCA exemptions, Stanford law professor, Jennifer Granick,
specifically stated that the FCC does not prohibit handset locking.