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:
GSM/CDMA Table Courtesy of Wikipedia
lol I found my local carrier, Mid-Tex. Didn’t think it was big enough to be considered …
Voddafone ?? there big in uk 😀
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
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 .
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.
Thanks.
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?