Differences between unlocked GSM and CDMA phones

This topic is important when it comes to unlocking a GSM or CDMA phone because they don’t both work in the same way. It is because of the differences between them in regards to the hardware they use to connect to a network (SIM card versus no SIM card). 

In simple terms, GSM handsets use what is known as a Subscriber Identity Module (SIM) card. The more popular of the two technologies, GSM phones are found in most markets worldwide. This is largely because of the fact that GSM technology was the first of the two and when mobile phones started becoming popular in the late 1990’s, they offered better signal coverage. GSM networks are currently the only type of network used in the UK and many other countries. The SIM card itself is usually extremely accessible for the phone's owner as well, usually placed under the phones battery. It can be removed and replaced easily, allowing owners to switch between networks without a problem (if the phone is unlock - which you can do through us if your GSM handset still needs unlocking).

CDMA handsets don’t use a SIM card. Instead they connect to a network because that networks details are programmed into the handset itself. Therefore, when the phone is switched on, it automatically connects to the network whose details are embedded inside. Some of the most popular CDMA carriers (networks) are based in the US and include Verizon and Sprint. These can be a lot tricker to unlock, so we’ll run through how that’s done below.


GSM Unlocking

Because a GSM handset uses a SIM card (where the networks information is kept) the phones also have a universally recognised SIM lock placed on them. This lock dictates which SIM cards the phone is allowed to work with.

The process of unlocking a GSM phone is then made pretty simple. The SIM lock that each GSM device has is assigned an unlock code when the phone is created. This code is what we or any other unlocking company supply when an order is placed. The phone recognises this code and removes the SIM lock, allowing the phone to accept any compatible SIM card when it is inserted.


CDMA Unlocking

CDMA phones have the networks information programmed inside as opposed to on a SIM card, with therefore no SIM lock being needed. The process of unlocking a CDMA phone then requires the use of software, where the unlocker can access the phones programming and tweak it to work with a different network. This is literally done with a cable and a computer.


It’s important to mention that most modern handsets are now sold with both CDMA and GSM technology, although not all are. Because of this, if the handset you unlock was created with GSM only, you will not be able to connect to a network that only provides a CDMA signal. The phone just isn’t capable of transmitting the waves. In contrast, if you have a CDMA phone and have it unlocked, you also won’t be able to use a network that provides a GSM only signal.

So if you’re looking to unlock your phone make sure you know which type of network it is that you will be hoping to join.

Done. Promise.

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  • 0
    Rimal Jose

    Hi Darren, I have a question. If a CDMA phone is unlocked, then how can it be used with another network/sim? Does the CDMA phones have a sim card slot or something??

  • 0
    Chad Matovu

    so how can I unlock a CDMA phone?

  • 0

    this doesn't make sense because verizon is a cdma network, but i have a sim card

  • 0
    Brian Tuminelly

    I can speak to Verizon's phones all of there 4g phones are Hybrids supporting both CDMA, GSM, and LTE networks.  LTE is typically considered a GSM evolution path. Most of there phones 4G phones have gsm and cdma built in. The difference is LTE bands Verizon, at&t,sprint and T-mobile use different frequencies to deliver there service. So you could use a Verizon phone on a T-mobile or At&t but probably wont get the full speed of there network. And All of Verizon's 4g phones have sim cards and use OTA programming for both there cdma network and LTE network. Even with the Verizon and Sprint the days of cdma are numbered they technically don't need the old tech for anything but are still using it. I have used unlocked GSM phones on verizons network the data (LTE) portion works flawlessly but they are still using CDMA for voice and text.

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