Unlocking 101: Difference Between CDMA and GSM

Information on GSM vs CDMA Unlocking:

Your average user doesn’t know that there are two major different technologies used for cell phones in the world; CDMA and GSM. While the majority of the world uses GSM, there are a few CDMA carriers scattered around the world. Here in the US though, it’s about 50% CDMA and 50% GSM (one of the only countries to have such a high use of CDMA technology). Now, I won’t get into the differences between the two technologies in detail here as this is mainly focusing on how one must go about unlocking each of these technologies, we’ll save that for another post…

The main difference you need to know is that GSM uses a SIM card, and CDMA does not. CDMA has the carrier’s information they want you to use the phone on stored in the phone’s programming, whereas GSM phones have a semi-universal software security lock placed on the SIM card slot that tells the phone what SIM card is allowed to be used.

Because of this, GSM phones can be unlocked using a passcode that the manufacturer has (or that can be generated using a keygen similar to a keygen for a hacked cd rom for your computer). Once that passcode is entered the phone will allow the use of any SIM card in the SIM card slot.
CDMA, on the other hand, doesn’t have this unlocking passcode feature since it doesn’t have the GSM standard locking mechanism. Instead, CDMA phones must literally be physically flashed with different firmware that has the new CDMA carrier’s information in it for the phone to access that new network (in other words, to unlock a CDMA phone you need to literally plug it in and use a flashing software to flash the carrier you want to use’s information onto the phone).

VERY IMPORTANT: No matter what you do to unlock a GSM/CDMA phone, they will ONLY work on a network with the same technology. So if you unlock a GSM phone, it will work on other GSM networks, but it will never work on a CDMA network (since there is no SIM card to put in the phone) and vise versa.

*There is one exception to this rule. Some CDMA phones are made to be used as a dual CDMA/GSM phone. This is sometimes called “World Edition” and is used simply because if you take your CDMA phone from the US overseas (where this is very little CDMA carriers), you would not be able to use your phone UNLESS the phone is dual GSM/CDMA. Popular phones that do this are usually Blackberry devices and you can tell which they are because they have a SIM card slot under the battery.
These dual CDMA/GSM phones CAN have the GSM slot unlocked via an unlock code (just like a normal GSM phone) and then you can use it on a GSM network of your choice (and just not use the CDMA part of the phone).

Confused, yet? Ok, it’s table time:

GSM	CDMA
Uses a SIM card slot	Does NOT use a SIM card slot.
Universal locking method means that all GSM locked phones have similar locks (which in turn means universal unlocking methods)	Carrier information stored in the phone’s software. There is no built in locking software mechanism, so there is no simply unlocking method.
GSM uses a passcode to lock the phone to a particular network’s SIM card. The passcode is needed one time to unlock the phone and allow a different SIM card to be used.	CDMA phones must be flashed in person using a cable in order to get it to use a different CDMA network.
The unlocking codes can be received from the manufacturer of the phone, or through a keygen program. This means the phone can be unlocked remotely with such a code.	You must find a CDMA flasher/unlocker in your area to flash the phone to a different CDMA carrier you wish to use.
CANNOT BE USED ON A CDMA NETWORK REGARDLESS OF IF IT IS UNLOCKED OR NOT	CANNOT BE USED ON A GSM NETWORK REGARDLESS OF IF IT IS UNLOCKED OR NOT*

To Unlock Your Phone:

So in order to unlock a GSM phone, you can either get the code from you carrier or you can purchase one from an unlock code supplier, once you input the code, your phone will be able to use any GSM carrier you want by just swapping out the SIM card.

In order to unlock your CDMA phone, you need to find a CDMA flasher/unlocker in your area and physically bring them your phone for them to flash to whatever network you want (you must know what network you are planning to use as they can only flash it to one carrier at a time).

List of GSM/CDMA US Carriers:

If you are curious, here is a table to show you what carrier’s in the US are GSM/CDMA:

Operator	Voice Technology	Data Technology	Subscribers (in millions)	Ownership
7-Eleven Speak Out Wireless •MVNO using AT&T and Sprint Nextel	GSM, CDMA	GPRS	Unknown	7-Eleven, Inc.
Airlink Mobile •MVNO using Sprint	CDMA		Unknown	Airlink Mobile
Alaska Communications Systems	CDMA	CDMA2000, EV-DO	0.130 [1] (2010 April), 0.139 [2] (2009 September)	Alaska Communications Systems
Alaska Digitel	CDMA	CDMA2000, EV-DO	Unknown	General Communication
Alaska Wireless	GSM	EDGE, Wi-Fi	Unknown	Alaska Wireless
Amerilink Wireless	GSM	GPRS	Unknown	Amerlink Wireless
Appalachian Wireless	CDMA	CDMA2000, EV-DO	0.100 (2009 December)	Appalachian Wireless
ASTAC	GSM	GPRS, WiMax	Unknown	The Arctic Slope Telephone Association Cooperative
AT&T Mobility •Includes GoPhone Prepaid, Dobson Cellular, Edge Wireless and Centennial Wireless	GSM, UMTS, HSDPA	GPRS, EDGE, UMTS, HSPA	90.130 [3] (2010 July), [4] (2010 July)	AT&T
BeyondMobile •MVNO using Sprint	CDMA	CDMA2000, EV-DO	Unknown	Cbeyond
Blue Wireless	CDMA	CDMA2000	Unknown	Blue Wireless
Bluegrass Cellular	CDMA	CDMA2000, EV-DO	0.130 [5] (2005 May)	Bluegrass Cellular, Inc.
Broadpoint	GSM	GPRS, EDGE	Unknown	Petrocom Inc.
call4care	GSM		Unknown	ASPIDER Solutions
Cap Rock Cellular	GSM	GPRS, EDGE	Unknown	Cap Rock Telephone
Cellcom	CDMA	CDMA2000	Unknown	NSight Telservices
Cellular One of East Central Illinois	GSM	GPRS, EDGE	Unknown	Cellular Properties Inc.
Cellular One of San Luis Obispo	GSM	GPRS, EDGE	Unknown	SLO Cellular
Cellular One of East Texas	GSM	GPRS, EDGE	Unknown	TX-11 Acquisition LLC
Cellular One of East Arizona	GSM	GPRS, EDGE	Unknown	Smith Bagley
Cellular One of Northeast Pennsylvania	CDMA	CDMA2000, EV-DO	Unknown	South Canaan Cellular
Cellular One Bermuda	CDMA, UMTS	CDMA2000, EV-DO, HSPA	Unknown	Bermuda Digital Communications Ltd.
Cellular One Montana	GSM	GPRS, EDGE	Unknown	MTPCS, LLC.
Cellular South	CDMA	CDMA2000, EV-DO	0.700 [6] (2007 December)	Cellular South
Chariton Valley Wireless	GSM	GPRS, EDGE	Unknown	Chariton Valley Telephone Company
Cincinnati Bell Wireless	GSM, GAN, UMTS	EDGE, HSPA	0.523 [7] (2010 April)	Cincinnati Bell, Inc. (100%)
Clear and/or Clearw re		WiMAX	0.971 [8] (2010 April)	Clearwire (27%), Sprint Nextel (51%), others (22%)
Clear Talk	CDMA	CDMA2000	Unknown	NTCH
CloseCall America •MVNO using Verizon and Sprint	CDMA		Unknown	CloseCall America
Commnet Wireless	GSM, CDMA		Unknown	Commnet Wireless
Consumer Cellular •MVNO using AT&T	GSM	GPRS, EDGE	Unknown	Consumer Cellular
Cordova Wireless	GSM	GPRS	Unknown	Cordova Telephone
Corr Wireless •Being acquired by Cellular South	GSM	GPRS, EDGE	Unknown	Corr Wireless
Cory’s Mobile Tech Support •Authorized Page Plus Cellular and H2O Wireless Dealer	CDMA, GSM	EV-DO, CDMA2000	Unknown	Cory’s Mobile Tech Support
Cricket Communications •Includes Jump Mobile Prepaid	CDMA	CDMA2000, EV-DO	5.4 [9] (2010 April)	Leap Wireless
Cross Communications	GSM	GPRS, EDGE	Unknown	Cross Communications
DTC Wireless	GSM	GPRS, EDGE	Unknown	DTC Wireless Systems
Eclipse Mobile	CDMA	CDMA2000, EV-DO	Unknown	New World Innovators Inc.
Einstein Wireless	GSM	GPRS, EDGE	Unknown	Airadigm Communications
Element Mobile	CDMA	CDMA2000, EV-DO	Unknown	Element Mobile
Epic PCS	GSM	CDMA2000, EV-DO	Unknown	Epic Touch
GCI Wireless	GSM	GPRS, EDGE	0.128 [10] (2010 April), 0.120 [11] (2009 September)	General Communication
Golden State Cellular	CDMA	CDMA2000	Unknown	California RSA No.3
GTC Wireless •MVNO using AT&T	GSM		Unknown	Atrium Wireless Partners, LLC
i-wireless •MVNO using Sprint	CDMA	CDMA2000	Unknown	i-wireless
i wireless	GSM	GPRS, EDGE	Unknown	Iowa Wireless Serivces
Immix	GSM	GPRS, EDGE	Unknown	Immix
Indigo Wireless	GSM	GPRS, EDGE	Unknown	Indigo Wireless
Jitterbug Wireless •MVNO using Sprint and Verizon	CDMA		Unknown	Jitterbug Wireless
Jolt Wireless •MVNO using AT&T	GSM		Unknown	Jolt Wireless
KTC	GSM	GPRS	Unknown	Kaplan Telnet
Leap Wireless	CDMA	EV-DO	5.400 [12] (2010 April)	Parent of Cricket Communications & Jump Mobile
Liberty Wireless •MVNO using Sprint	CDMA		Unknown	TelePlus Enterprises, Inc.
Lightyear Wireless •MVNO using Sprint	CDMA	CDMA2000	0.060 [13] (2010 July)	Lightyear Network Solutions
Locus Mobile •MVNO using AT&T and Verizon	GSM, CDMA		Unknown	Locus Telecommunications
Long Lines Wireless	GSM	GPRS, EDGE	Unknown	Long Lines
Lucky Wireless •MVNO using Verizon and Sprint	CDMA		Unknown	Lucky Wireless
MetroPCS	CDMA	CDMA2000	7.331 [14] (2010 April), [15] (2010 April)	MetroPCS Communications, Inc.
Mid-Tex Cellular	GSM	GPRS, EDGE	Unknown	Mid-Tex Cellular
Movida Wireless •MVNO using Sprint	CDMA		0.267 [16] (2008 March)	Movida Communications, Inc.
NEP Wireless	GSM	GPRS, EDGE	Unknown	North-Eastern Pennsylvania Telephone
Nex-Tech Wireless	CDMA	CDMA2000, EV-DO	Unknown	Nex-Tech
nTelos	CDMA	CDMA2000, EV-DO	0.445 [17] (2010 April)	nTelos Holdings Corp.
Page Plus Cellular •MVNO using Verizon	CDMA	CDMA2000	Unknown	Page Plus Cellular
Pine Cellular	GSM	GPRS	Unknown	Pine Cellular
Pioneer Cellular	CDMA	CDMA2000, EV-DO	Unknown	Pioneer Cellular
Plateau Wireless	GSM	GPRS, EDGE	0.075	PlateauTel
PlatinumTel Prepaid Wireless •MVNO using Sprint	CDMA		Unknown	PlatiumTel Communications, LLC
Pocket Communications	CDMA	1xRTT	Unknown	Pocket Communications
Pure Mobile •MVNO using Verizon	CDMA		Unknown	Powered by Telrite
Pure Prepaid •MVNO using AT&T	GSM		Unknown	Powered by Telrite
Pure TalkUSA •MVNO using AT&T	GSM		Unknown	Powered by Telrite
Revol Wireless	CDMA	CDMA2000	Unknown	Cleveland Unlimited
ReadyMobile •MVNO using Sprint	CDMA	CDMA2000	Unknown	HH Ventures
Simmetry	GSM	GPRS, EDGE	Unknown	Simmetry
Shaka Mobile	GSM, CDMA	GPRS, EV-DO	Using AT&T, Sprint, Verizon	Shaka Mobile
SouthernLINC	iDEN		0.275 [18] (2008 April)	Southern Company
Sprint Nextel •Includes Sprint Network, Nextel Network, Boost Mobile, and Virgin Mobile USA •Wholesale and affiliates	CDMA, iDEN, UMTS	CDMA2000, EV-DO, WiMAX	47.818 [19] (2010 April)	Sprint Nextel Corporation
Stelera Wireless		HSPA	Unknown	Stelera Wireless LLC
STI Mobile •MVNO using Sprint	CDMA	CDMA2000	Unknown	STi Mobile
Syringa Wireless	CDMA	CDMA2000	0.00135	Syringa Wireless
TerreStar	GSM terrestrial and satellite	GPRS, EDGE, HSPA	Unknown	Terrestar Corporation
Thumb Cellular	CDMA	CDMA2000, EV-DO	0.037	Thumb Cellular
T-Mobile USA •Includes T-Mobile To Go Prepaid and SunCom	GSM, UMTS, GAN	GPRS, EDGE, UMTS, HSPA	33.713 [20] (2010 April), [21] (2010 April)	Deutsche Telekom
TracFone Wireless •MVNO using Claro Puerto Rico, AT&T, Verizon, Sprint, US Cellular and T-Mobile •Includes NET10 and Straight Talk	GSM, CDMA	GPRS, CDMA2000	15.452 [22] (2010 April), 14.427 [23] (2009 December)	América Móvil
Trumpet Mobile •MVNO using Sprint	CDMA	CDMA2000	Unknown	Affinity Mobile
Túyo Mobile •MVNO using T-Mobile	GSM	GPRS, EDGE	Unknown	IDT Corp.
Union Wireless	GSM	GPRS	Unknown	Union Telephone
U.S. Cellular •Includes TalkTracker Prepaid	CDMA	CDMA2000, EV-DO	6.147 [24] (2010 April)	U.S. Cellular Corporation
Verizon Wireless •Includes INPulse Prepaid, Unicel and Alltel	CDMA, UMTS	CDMA2000, EV-DO, LTE (Late? 2010)	92.063 [25] (2010 July), [26] (2010 July)	Verizon Communications (55%) and Vodafone (45%)
Viaero Wireless	GSM	GPRS, EDGE	Unknown	Viaero Wireless
Virgin Mobile USA •MVNO using Sprint •Includes Helio	CDMA	CDMA2000, EV-DO	Unknown	Sprint Nextel
West Central Wireless	GSM	GPRS, EDGE	Unknown	West Central Wireless
Westlink	GSM	GPRS, EDGE	Unknown	Westlink Communications
Working Assets Wireless •MVNO using Sprint	CDMA		Unknown	Working Assets
XIT Communications	GSM	GPRS, EDGE	Unknown	XIT Communications
Xtreme Mobile •MVNO using Sprint	CDMA		Unknown	Xteme Mobile

GSM/CDMA Table Courtesy of Wikipedia