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:

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.

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)
7-Eleven Speak Out Wireless
MVNO using AT&T and Sprint Nextel
GSMCDMA GPRS Unknown 7-Eleven, Inc.
Airlink Mobile
MVNO using Sprint
CDMA Unknown Airlink Mobile
Alaska Communications Systems CDMA CDMA2000EV-DO 0.130 [1] (2010 April), 0.139 [2] (2009 September) Alaska Communications Systems
Alaska Digitel CDMA CDMA2000EV-DO Unknown General Communication
Alaska Wireless GSM EDGEWi-Fi Unknown Alaska Wireless
Amerilink Wireless GSM GPRS Unknown Amerlink Wireless
Appalachian Wireless CDMA CDMA2000EV-DO 0.100 (2009 December) Appalachian Wireless
ASTAC GSM GPRSWiMax Unknown The Arctic Slope Telephone Association Cooperative
AT&T Mobility
•Includes GoPhone Prepaid, Dobson CellularEdge Wireless and Centennial Wireless
GSMUMTSHSDPA GPRSEDGEUMTSHSPA 90.130 [3] (2010 July), [4] (2010 July) AT&T
MVNO using Sprint
CDMA CDMA2000EV-DO Unknown Cbeyond
Blue Wireless CDMA CDMA2000 Unknown Blue Wireless
Bluegrass Cellular CDMA CDMA2000EV-DO 0.130 [5] (2005 May) Bluegrass Cellular, Inc.
Broadpoint GSM GPRSEDGE Unknown Petrocom Inc.
call4care GSM Unknown ASPIDER Solutions
Cap Rock Cellular GSM GPRSEDGE Unknown Cap Rock Telephone
Cellcom CDMA CDMA2000 Unknown NSight Telservices
Cellular One of East Central Illinois GSM GPRSEDGE Unknown Cellular Properties Inc.
Cellular One of San Luis Obispo GSM GPRSEDGE Unknown SLO Cellular
Cellular One of East Texas GSM GPRSEDGE Unknown TX-11 Acquisition LLC
Cellular One of East Arizona GSM GPRSEDGE Unknown Smith Bagley
Cellular One of Northeast Pennsylvania CDMA CDMA2000EV-DO Unknown South Canaan Cellular
Cellular One Bermuda CDMAUMTS CDMA2000EV-DOHSPA Unknown Bermuda Digital Communications Ltd.
Cellular One Montana GSM GPRSEDGE Unknown MTPCS, LLC.
Cellular South CDMA CDMA2000EV-DO 0.700 [6] (2007 December) Cellular South
Chariton Valley Wireless GSM GPRSEDGE Unknown Chariton Valley Telephone Company
Cincinnati Bell Wireless GSMGANUMTS EDGEHSPA 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 GSMCDMA Unknown Commnet Wireless
Consumer Cellular
MVNO using AT&T
GSM GPRSEDGE Unknown Consumer Cellular
Cordova Wireless GSM GPRS Unknown Cordova Telephone
Corr Wireless
•Being acquired by Cellular South
GSM GPRSEDGE Unknown Corr Wireless
Cory’s Mobile Tech Support
•Authorized Page Plus Cellular and H2O Wireless Dealer
CDMAGSM EV-DOCDMA2000 Unknown Cory’s Mobile Tech Support
Cricket Communications
•Includes Jump Mobile Prepaid
CDMA CDMA2000EV-DO 5.4 [9] (2010 April) Leap Wireless
Cross Communications GSM GPRSEDGE Unknown Cross Communications
DTC Wireless GSM GPRSEDGE Unknown DTC Wireless Systems
Eclipse Mobile CDMA CDMA2000EV-DO Unknown New World Innovators Inc.
Einstein Wireless GSM GPRSEDGE Unknown Airadigm Communications
Element Mobile CDMA CDMA2000EV-DO Unknown Element Mobile
Epic PCS GSM CDMA2000EV-DO Unknown Epic Touch
GCI Wireless GSM GPRSEDGE 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
MVNO using Sprint
CDMA CDMA2000 Unknown i-wireless
i wireless GSM GPRSEDGE Unknown Iowa Wireless Serivces
Immix GSM GPRSEDGE Unknown Immix
Indigo Wireless GSM GPRSEDGE 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 CommunicationsJump 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
GSMCDMA Unknown Locus Telecommunications
Long Lines Wireless GSM GPRSEDGE 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 GPRSEDGE Unknown Mid-Tex Cellular
Movida Wireless
MVNO using Sprint
CDMA 0.267 [16] (2008 March) Movida Communications, Inc.
NEP Wireless GSM GPRSEDGE Unknown North-Eastern Pennsylvania Telephone
Nex-Tech Wireless CDMA CDMA2000EV-DO Unknown Nex-Tech
nTelos CDMA CDMA2000EV-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 CDMA2000EV-DO Unknown Pioneer Cellular
Plateau Wireless GSM GPRSEDGE 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
MVNO using Sprint
CDMA CDMA2000 Unknown HH Ventures
Simmetry GSM GPRSEDGE Unknown Simmetry
Shaka Mobile GSMCDMA GPRSEV-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
CDMAiDENUMTS CDMA2000EV-DOWiMAX 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 GPRSEDGEHSPA Unknown Terrestar Corporation
Thumb Cellular CDMA CDMA2000EV-DO 0.037 Thumb Cellular
T-Mobile USA
•Includes T-Mobile To Go Prepaid and SunCom
GSMUMTSGAN GPRSEDGEUMTSHSPA 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
GSMCDMA GPRSCDMA2000 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
Union Wireless GSM GPRS Unknown Union Telephone
U.S. Cellular
•Includes TalkTracker Prepaid
CDMA CDMA2000EV-DO 6.147 [24] (2010 April) U.S. Cellular Corporation
Verizon Wireless
•Includes INPulse Prepaid, Unicel and Alltel
CDMAUMTS CDMA2000EV-DOLTE (Late? 2010) 92.063 [25] (2010 July), [26] (2010 July) Verizon Communications (55%) and Vodafone (45%)
Viaero Wireless GSM GPRSEDGE Unknown Viaero Wireless
Virgin Mobile USA
MVNO using Sprint
•Includes Helio
CDMA CDMA2000EV-DO Unknown Sprint Nextel
West Central Wireless GSM GPRSEDGE Unknown West Central Wireless
Westlink GSM GPRSEDGE Unknown Westlink Communications
Working Assets Wireless
MVNO using Sprint
CDMA Unknown Working Assets
XIT Communications GSM GPRSEDGE Unknown XIT Communications
Xtreme Mobile
MVNO using Sprint
CDMA Unknown Xteme Mobile

GSM/CDMA Table Courtesy of Wikipedia

11 thoughts on “Unlocking 101: Difference Between CDMA and GSM”

  1. Dude.. grow up.. there is the facility of SIM’s in CDMA phones.
    thoough the change happened a year ago only.
    CDMA can be hacked to used as a GSM1

  2. David … now that i have this EVo 4g from sprint and i am planning to use it with another cdma provider in my home country , can i do flash the phone some how … How do i do it ..? will cdma workshop help … any links posts will be helpful .

  3. Hi

    Just wondering if the verizon Motorola xoom can b unlocked to uk networks as it has a sim slot on it but doesn’t work.
    Any info would be great.


  4. So I have a tmobile blackberry bold and I’m willing to do anything to get it to work with ANYONE ELSE other than tmobile and at&t… any suggestions outside of buying a new $200 phone?

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