Unlock Your Phone

Unlock Your Phone

Unlock your phone so that it works with all network operators when you travel or switch plans. It is your phone. Take control of it!

If you bought your phone from a mobile operator, chances are very good that it's locked to the operator's network. While the phone itself might be compatible with all GSM networks (i.e., a triband phone), it rejects SIM cards from other GSM operators. Locking imposes some limitations on how you can use your phone:

  • If you change your service plan to that of another operator, you will not be able to continue using the locked phone. You will have to buy a new phone and transfer all the data.

  • The locked phone probably will not work with prepaid calling cards in foreign countries, since the prepaid service requires a new SIM card from a local operator. See "Use Prepaid Calling Cards" [Hack #28] for more on prepaid mobile phone calling cards.

  • If you no longer use an old phone, it is difficult to sell or donate it if it is locked, as you have to require that the buyer or recipient has the same wireless operator as you do to make sure the phone functions as promised.

If you place a SIM card from another operator into a locked Nokia phone, it will display messages such as "Enter restriction code" or "SIM card rejected," and will refuse to even display the Main menu.

If the error message is related to a SIM security code, or if it reads something like "SIM registration failed," you might not be able to connect to the network, but the phone is indeed unlocked. The acid test is to see whether you can access the Main menu. If you can, the phone is unlocked; if you can't, the phone is locked.

The rationale for operator locking is that the operator subsidizes the phone's price via service charges. So, it should do something to prevent the user from switching to other operators' services with the subsidized phone. However, from the customer's point of view, this is not a convincing argument, as the subsidy should be considered part of the marketing and customer acquisition cost. In fact, in most mobile service agreements, nothing prohibits you from unlocking the phone (check your service agreement to make sure this applies to you). In addition, the operator has no way of knowing whether your phone is locked.

As the legitimate owner of the phone, why should you put up with those limitations? In this hack, you will learn how to unlock and take control of your phone. An unlocked triband Nokia GSM phone will work with almost any GSM operator in the world. It is your phone, after all.

If you bought your phone from an electronics store without a specific mobile service plan, it is probably unlocked and will work with all operators.

Just Call the Operator

Before you try anything yourself, you should call the mobile service operator's customer service department to see whether they are willing to unlock the phone for you for free. Some operators will unlock your phone under some circumstances. For example, T-Mobile USA might help you unlock your phone when you switch out of its service after the original service plan has expired. But the operator might charge an expensive fee ($40 or so for each phone) for such an unlocking service. In any case, call customer service and ask for a free unlock codeit never hurts to try.

If the operator agrees to unlock your phone, the customer service representative will give you a "remote unlock code" over the phone or via SMS. The code consists of numerical digits, the letters p and w, and the + sign.

You need to write down the code very carefully. Then, take the SIM out of the phone, turn on the phone, and enter the code. Press the * key four times within one second to get the letter w; three times within one second to get the letter p, and twice within one second to get the + sign.

If the unlocking is successful, the phone pops up a message indicating it has been unlocked (e.g., "phone restriction off"). You can put the SIM back in the phone and then power up, and you'll be back in business!

It is very important to stress that you need to verify the unlock code and enter it very carefully. If you make a mistake, you can reboot the phone and try it again. But if you make a mistake five times in a row, the phone will not allow you additional attempts. You'll have to take the phone to a repair shop to get it unlocked in this case.

The operator-assisted unlocking service is easy and reliable. However, not all operators provide such services, and even those that do probably charge an expensive service fee. Of course, better and free (or very low-cost) alternatives are available from mobile hackers and third-party vendors. You will learn all about such solutions in the rest of this hack.

Calculate the Code Yourself

To calculate the unlock code, you need to download a code calculator program. Many code calculators are available as freeware, and others are for-pay shareware or commercial software. In general, the freeware calculators have a less-polished UI and require you to know more technical jargon.

Calculating unlock codes using freeware calculators can be frustrating. If you do not enjoy searching the Internet and experimenting with software tools, I highly recommend that you use one of the low-cost unlock code services listed in Figure, later in this chapter. This section is provided primarily for educational purposes.

You can find a comprehensive list of unlock code calculator programs from this web page: http://www.unlockme.co.uk/downloads.html. Not all calculators run on all flavors of Windows operating systems, and not all of them can calculate unlock codes for all Nokia models and all operators. So, you might have to download and experiment with multiple calculators. I recommend you try the CyberGSM, Hollowman, DCT4NCK, and NokiaFREE calculators listed on preceding sites.

NokiaFREE has an online calculator at http://unlock.nokiafree.org/, which does the same thing as the Windows client software.

If the link on the web site goes out-of-date, you can simply search for the calculator name on Google and you will probably find a link to it. But for most freeware programs downloaded off an unknown web site, you need to be very careful with security. You should check the download with antivirus software and run it only in nonadministrator mode. Or better yet, run the calculator in an emulated Windows environment. Popular PC emulators are Virtual PC, VMware, and the excellent and free QEMU (http://fabrice.bellard.free.fr/qemu). The PC emulators also allow you to run those Windows-based unlock code calculators on Mac and Linux computers.

Few freeware calculators can compute unlock codes for older Nokia models with the DCT3 firmware (NokiaFREE does, however). Most of today's Series 40 and Series 60 phones use the DCT4 firmware, which almost all calculator programs support. You can see a list of DCT3 phones at http://www.unlockme.co.uk/softwareversions.html. If your phone is not listed in the DCT3 table, it is probably a DCT4 phone.

Now, let's go through the calculation process using a basic (and early) freeware unlock code calculatorthe DOS/Windows command-line utility, DCT4NCK (available from http://homepage.ntlworld.com/danluik/downloads/ dct4nck.zip). Figure shows DCT4NCK running under Windows 95 in QEMU. All the other unlock code calculators work similarly.

Generating unlock codes from the relative safety of an emulator

Once you run the dct4nck command from a DOS (shell) window, you will see the following usage message:

DCT4NCK by jozso v0.0a
Usage: dct4nck locktype imei provider [boxserial]

The locktype, according to http://unlockme.co.uk, is usually 2, unless you're on a 3650 or 7650, in which case it's 5. The IMEI is the hardware serial number of your phone [Hack #5]. Finally, you'll need the provider code, which is a number you can pull from a network provider code list such as the one at http://www.yeldar.co.uk/MCC-MNC.htm.

The calculator generates seven different codes, at least one of which should unlock the phone when you enter it with the SIM removed, but you get only five tries before the phone locks you out. So, you really want to double-check your work before entering would-be unlock codes into the phone.

Typically, you want to try the fourth one first, then the first one, and then the seventh one.

Although the unlock code calculation process might sound easy, it has several caveats, especially with freeware calculators. For instance, the following notes about AT&T Wireless's Nokia 3650 are available on the http://unlockme.co.uk/ web site:

  • Although a provider code for AT&T is listed in the network provider list at http://www.yeldar.co.uk/MCC-MNC.htm, Nokia 3650 users on AT&T Wireless have a variety of codes to choose from depending on their phone's IMEI.

  • For Nokia 3650 on AT&T USA, always use the first code out of the seven generated.

The notes and exceptions will continue to increase as new phone models are released and operators find more ways to make unlocking more difficult. Your best bet is to take the time to read everything you can find at http://unlockme.co.uk.

Of course, it is possible to keep track of those exceptions and integrate them into the logic of the unlock calculator software. For instance, the program could just ask you the phone model, IMEI, and operator name. If you enter Nokia 3650 and AT&T, it should be able to figure out the correct operator code automatically, and it should return only the first unlock code. But most freeware authors do not have the time for such extensive research and do not tend to keep their program updated after its release. You have to live with those inconveniencesyou're getting the software for free, after all.

Get Professional Help

By now, you probably have concluded that you do not want to go through the hassle of calculating the unlock code yourself, for the following reasons:

  • Running untrusted Windows software is never a very good idea.

  • If you miss one rule exception, you will not get the correct unlock code.

  • Even if you do get the calculator working correctly, you typically get seven codes, and the phone allows only five attempts before it locks itself up.

The good news is that you do not need to calculate the unlock code yourself or beg the operator for it. For a couple of dollars, you can get an expert to calculate it for you using the most up-to-date software. Then you can receive the unlock code instantaneously via phone or the Web. For most users, that is the best way to unlock a phone. Figure shows a list of popular unlocking services. All prices are current as of April 2005.

Popular unlock code services

Web site





One British pound per minute, with each case lasting about five minutes


All Nokia devices on any UK network




Operators around the world




Operators in North America and the Philippines




Some selected UK and U.S. operators




Operators around the world




Operators around the world

Once you get the unlock code, you can enter it into the phone using the remote unlocking instructions discussed earlier in this hack. Or, you can simply follow the instructions provided by the unlocking service.

Use a Cable-Based Solution

An alternative solution to remote locking is to unlock the phone using data cables. The cable-based solution is your only choice if you failed to remotely unlock the phone after five attempts. (As noted earlier, the phone automatically locks itself after five attempts.)

Cable-based solutions can be complex. And if you do not know what you are doing, you can permanently damage your phone. Hence, if you are a casual mobile phone user, I highly recommend you find a professional mobile phone service shop to do the unlocking. These shops have special devices known as unlocking clips, which are preloaded with the latest commercial unlocking software. All they have to do is just hook the unlocking clip with the phone via a cable and press a button, and the phone is unlocked. These professionals can also reflash the entire phone firmware and return it to its factory setting via a cable connection. This way, you can get rid of any security code and clear past failed unlock attempts.

Of course, you can buy an unlocking clip yourself, but it is expensive, so it's not economically feasible if you're buying it to unlock only a couple of devices.

To do cable-based unlocking, you need to purchase a serial or USB cable for your phone from web sites such as http://ucables.com/cables/Nokia. You need MBus interface cables to work with most unlocking software. Those cables cost around $50 each. After hooking up the phone with the computer, you can use software such as JIC DCT4 Unlocker (http://homepage.ntlworld.com/danluik/downloads/JIC%20dct4%20unlocker.zip) to unlock the phone directly from the computer. Some programs also allow you to reset the security codes, etc., for some phone models. You can read more about various cable-based unlocking solutions at http://unlockme.co.uk/.

You also can use the data cable with the Nokia PC Suite to transfer data between the phone and the computer [Hack #15].

This hack is based in part on an O'Reilly Network article (http://www.oreillynet.com/pub/wlg/3935) written by Schuyler Erle.

Michael Yuan

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