Unlocking GSM Handsets
by The Prophet
Ever wonder why most cellular carriers gladly give you a "free" phone?
It's probably because they have "locked" the phone to their network so you can't use it with any other carrier. At least, that's the theory. In practice you can often unlock your handset and use it with another carrier.
Why should you care about unlocking your handset?
Perhaps your phone broke and the replacement handset you bought off eBay was sold by another carrier - so with your SIM, all it does is display "network barred."
You might want to try out a friend's phone and see whether it's right for you... but you have AT&T and he has T-Mobile.
What if you hate your carrier but love your phone and you want to switch it to another provider? Too bad it's a locked handset because you can't do it... or can you?
Maybe you just don't want you cellular phone company telling you which carriers you're allowed to use.
Whatever the reason, it's your phone. You paid for it, and whether or not your carrier wants you to do so, it's your right to unlock it.
Best of all, it's still legal (in most areas - for specific legal advice concerning your situation, always consult an attorney.)
Depending on the particular model of GSM handset you have, it can be anywhere from really easy to almost impossible to unlock it.
This article will focus on the Nokia DCT4 series handsets which are the following model numbers: 3510i, 6100, 8910, 8910i, 8310, 6510, 6310, 6310i, 6650, 6800, 7210, 7250, 6610, 3650, and 7650
This series of handsets falls into the "easy" category and can be unlocked directly from they keypad.
Before you begin, obtain the following information:
IMEI: Remove the battery. Your 15-digit IMEI will appear on a white sticker.
Model Number: Appears next to the IMEI sticker.
Network Provider Code: The numerical identifier of your GSM provider.
Some common network provider codes are as follows:
- 31038: AT&T Wireless
- 31015: Cingular (East Coast)
- 31017: Cingular (West Coast)
- 31016: T-Mobile (East Coast)
- 31026: T-Mobile (West Coast)
- 31031: T-Mobile (Florida)
Note: There can be some trial-and-error associated with the network provider code since these change frequently. If you're not sure of the network provider code for your carrier, be sure to research and obtain the correct code before attempting to unlock your phone. You are only allowed five unlock attempts!
Next, download and install a DCT4 calculator. A good one is located at the following URL: uniquesw.com. If this page no longer exists, search the Web for [DCT4 calculator] and you should find one.
In the DCT4 calculator, type your IMEI and network provider code (some DCT4 calculators refer to this as an "operator code").
Additionally, select the type of phone you have.
Double-check that everything is correct and calculate your unlock codes.
A result similar to the following example will be displayed:
The first four codes displayed are Lock codes.
The final three codes are Unlock codes.
You will probably want to use the Master Unlock code (ending in 7#) because it unlocks everything.
All right, you're ready to go!
Take the SIM card out of your phone and then power it on. When your phone displays Insert SIM, enter the unlock code at the bottom of the list (ending in 7#), exactly as shown in the calculator:
To enter the + character, press the * key twice.
To enter the p character, press the * key three times.
To enter the w character, press the * key four times.
You phone should pause briefly and then display a Restriction Off message.
Congratulations! Your Nokia GSM handset is now unlocked and will accept SIM cards from any carrier.
Troubleshooting
If things don't work as expected, confirm that you didn't make any data entry errors and then try again. If you still have trouble, you may want to review the references and message boards below.
You only get five tries to get this right before your phone locks you out of the service menu, so if you don't know what you're doing, ask someone who does!
There are plenty of GSM hackers out there who will to glad to help.
References
DCT4 Calculator: uniquesw.com
Nokia Unlocking FAQ: gsmsearch.com/faq/nokiaflasher.html
Nokia Unlocking Message Boards: nokiafree.org
General Wireless Message Boards: howardforums.com, wirelessadvisor.com
Appendix: North American PCS Technology
In North America, there are four widely available digital (often marked as "PCS") technologies in use, along with the legacy (and still operational) AMPS analog cellular network.
While the above article is about unlocking GSM phones, CDMA phones can also be "locked" to a particular carrier through a method called Master Subsidy Lock (MSL).
What follows is a list of PCS technologies:
CDMA: Used primarily by Verizon, Alltel, U.S. Cellular, Qwest, and Sprint PCS. CDMA service is operated on both the 800 MHz cellular and 1900 MHz PCS frequencies. This technology supports both voice and data applications. There are two variants of CDMA in wide use. The newer version, 1xRTT, allows for data speeds of 144 kbps, has better call quality, and offers greater spectral efficiency for voice applications. The older version, IS-95, supports data speeds of up to 14.4 kbps and uses a less efficient voice codec.
TDMA: Used primarily by AT&T and Cingular. TDMA is a legacy technology that supports only voice applications. It operates only in the 800 MHz cellular frequencies and is being phased out by both carrier in favor of GSM.
iDEN: Available only from Nextel in the U.S. and Telus MiKE in Canada. This is a proprietary Motorola technology that supports voice, data, and "walkie-talkie" features. It operates on two-way radio frequencies in the 800 MHz range.
GSM: Available from AT&T, Cingular, T-Mobile, and other carriers. Primarily operates in the 1900 MHz "PCS" frequencies but many carriers are beginning to offer service in the former 850 MHz TDMA spectrum. While widely considered to offer better voice quality than CDMA, GSM is much less spectrally efficient. Additionally, GSM does not offer "soft hand-offs" like CDMA, making it more prone to dropped calls. Data services, called GPRS, are circuit-switched and operate up to 56 kbps.
Acknowledgments
UniqueSW - for their excellent - and free - DCT4 calculator.
Nokiaguru - for the Nokia Unlocking FAQ, without which I'd never have used the above calculator successfully.