What Does GSM Unlocked Mean? All You Need To Know

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Deyan Georgiev
Written by
Deyan Georgiev

Updated · Aug 17, 2023

Deyan Georgiev
Website Manager | Joined October 2021 | LinkedIn
Deyan Georgiev

Deyan is an avid enthusiast and self-proclaimed fan of the Windows operating system. His passion for... | See full bio

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Joined November 2021
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A SIM is a feature most phone manufacturers enable to lock in certain SIM carriers to users. This aims to reduce fraud and theft risk, ensuring the user uses the phone through an official network carrier.

GSM locks also create high-quality phones more affordable due to partnerships between phone manufacturers and network providers. However, this prevents users from swapping to their ideal SIM cards if needed. 

📖 GSM Definition:

The Global System for Mobile, commonly called the GSM, is a standard technology for most cellular networks worldwide. GSM-unlocked phones can be used with any SIM provider using GSM technology.

Owning a phone with a GSM lock can be frustrating, making switching to a locally supported network hard. To maneuver this, there are many options you can try to unlock a GSM-locked phone.

In this article, learn what GSM unlocked means, its similar terms, and how to remove the GSM lock on a phone. Begin by scrolling below.

🔑Key Takeaways:

  • GSM Unlock allows you to use other SIM cards besides the one you bought with your phone.
  • Although GSM unlocking makes your phone compatible with most SIM cards, a few exceptions exist, like Verizon, Sprint, and other non-GSM networks.
  • Before unlocking your phone, you should confirm whether it is SIM locked and what network it uses.
  • You can unlock your phone by contacting your service provider, using software or hardware, or using your device’s IMEI.

GSM Unlock: What Does It Mean?

When your phone has a SIM lock, it asks for a unique code when you insert another SIM card. By GSM-unlocking your phone, you can easily switch to other SIM cards without getting locked into your mobile device.

This is usually done using the IMEIs attached to devices during manufacturing. IMEIs are 15-digit numbers unique to every mobile phone, serving as the device's unique identity or "name." By accessing your IMEI, companies, and individuals can change and monitor the status of your phone.

☝️ Did You Know?

You can also use your IMEI to track your mobile device. Check out Techjury’s article on tracking someone’s location with just a phone number.

New phones are typically GSM-locked, depending on the location or SIM carrier. In contrast, other phones are available as GSM-unlocked, factory-unlocked, or fully unlocked.

The next section below will delve into the differences between phone SIM locks, but first, let’s start by defining what factory-unlocked means.

Defining Factory-Unlocked

Factory-unlocked GSM phones are compatible with any SIM carrier or network. Smartphone users can use any SIM card for these phones, ensuring seamless network connectivity. They are also suitable for international travelers or those who frequently switch carriers.

You can tell if a phone is GSM unlocked with the following:

  1. Accepts Any SIM Card - Phones with SIM cards from multiple carriers likely have GSM unlocked capabilities.
  2. Factory Unlocked Label - Factory unlocked phones are untied to a specific carrier, enabling use with any preferred GSM network provider.
  3. No Network Limitations - Check phone specifications for GSM unlocked compatibility with multiple carriers, indicating network compatibility with different networks.

On the other hand, your phone may be showing signs that it is factory-unlocked but cannot accept a SIM card. There are many reasons, but the most likely is that it is not CDMA-unlocked.

👍Helpful Article: 

A SIM card is more than just a piece of plastic containing your phone number; it also holds 14 codes, pins, and numbers. Learn more by reading TechJury’s article on what data is stored on SIM cards.

What Does CDMA Unlocked Mean?

CDMA, or Code Division Multiple Access, uses 2G or 3G networks. Unlike GSM, CDMA phones cannot process more than 2 points of data at the same time, making them difficult to use. 

With this, a CDMA-unlocked phone allows it to work with GSM carriers, giving the phone complete access to GSM’s features. This allows for a more convenient device experience for users.

The table below summarizes the difference between the GSM and CDMA technology in SIM cards.



Identifies and verifies users with SIM cards.

Use a unique code instead of SIM cards.

Moving your SIM card to a new phone makes switching phones easy.

This complicates phone activation as the carrier must first activate the new device on the network.

Divides calls and data into time slots so multiple users share the same frequency

Allows multiple users to transmit data simultaneously over the same frequency using different codes

Each call or data session gets a specific time slot

It uses spread spectrum technology to spread the signal over a wider frequency range.

Widely used globally and is the dominant standard in most countries

Used by some carriers in the USA and a few other countries.

Networks: AT&T, T-Mobile, Vodafone, O2, Airtel, Telstra, MTN

Networks: Verizon, Sprint, US Cellular, Bell Mobility, Telus Mobility, China Telecom, KDDI, SK Telecom

Overall, having a GSM-unlocked phone doesn't mean it's also compatible with CDMA. Likewise, unlocking the phone for either differs from full unlocking. The cost of each may also vary.

🎉 Fun Fact:

CDMA technology has inherent noise-rejection capabilities, contributing to its popularity in the early days of cellular networks. This noise immunity made it more resistant to interference, providing better call quality in crowded areas.

GSM Unlock vs. Fully Unlocked vs. GSM Network Cell Phone: What's the Difference?

A GSM-unlocked phone isn’t automatically compatible with all other SIM cards. In general, GSM-unlocked phones can only work with:

  • AT&T, T-Mobile
  • Verizon (the 4G LTE variants only)
  • Cricket Wireless
  • Metro
  • Simple Mobile
  • H2O Wireless
  • Ultra Mobile

Aside from GSM, there are other technologies, like CDMA. Some examples of CDMA-based networks are:

  • Verizon Wireless
  • Sprint, US Cellular
  • Boost Mobile
  • Virgine Mobile
  • C Spire
  • Bluegrass Cellular
  • Ntelos Wireless

Through the table below, let’s examine the difference between GSM unlock, fully unlocked, and GSM network cellphones.


GSM Unlock

Fully Unlocked

GSM Network Cell Phone


Uses GSM technology and only operates with support providers.

Supports GSM and CDMA technology and works with any carrier.

Specifically designed for GSM networks only.


Can be used with different carriers

Compatible with a wide range of networks.

Limited to GSM-compatible networks only.

SIM Card

Requires compatible SIM card for activation

Requires compatible GSM SIM card for activation


Using a GSM unlocked phone with any SIM card

Using a fully unlocked phone with any SIM

Using a GSM network phone with a GSM carrier.

Understanding the distinctions between GSM Unlocked, Fully Unlocked, and GSM Network Cell Phones can aid in determining the most suitable method for removing the SIM lock.

Essential Steps to Take Before Unlocking Your Phone

To unlock your phone carrier, first understand your network and policies. Tap on SIM Status and select a network provider. Many networks have pre-installed unlocking apps or prompts in Settings. If encountering issues, contact the network provider through their website.

Below is a list of the mobile phone providers offering unlocking, their customer support contact information, and their pros and cons.

Carrier Contact Info




You can easily check your unlock request status.

Does not unlock devices bought in installments.


Easy unlocks both iPhone and Android.

Cricket locks and unlocks phones after six months of active use.

Metro by T-Mobile

You can unlock your device within two business days.

It should be at least 180 days since your device's activation.


Automatically removes the lock after 60 days of activation.

More expensive than other network providers.

After confirming that your phone is locked, you can now weigh which method is applicable in your case.

4 Methods of How to GSM Unlock a Phone

Four GSM Unlocking Methods with Pros and Cons

Unlocking a GSM phone is becoming more accessible, but it's crucial to understand the method's implications and potential risks.

Let’s discuss the popular methods below

Method 1: Contact Your Service Provider (Best for Newbies with No Time Constraints)

Contacting your service provider is the easiest and safest method. This method passes the work onto the manufacturers who know the most about your phone or SIM card. 

Before doing this, it’s important to note that each service provider has specific policies for GSM unlocking. Here are the general requirements that most service providers will look at:

  • The phone was bought using a postpaid plan from that service provider company.
  • The account was active within the last 60 days.
  • The bills are paid on time.
  • The device was not recently reported lost, blocked, or stolen.

You can check more about them by consulting the customer service mentioned earlier. Meanwhile, here are the basic steps to using this method:

  1. Check your phone's Settings > Network to see if there's an option to unlock your phone. If there is, skip Step 2 and proceed with the instructions on your phone).
  2. Contact your service provider.
  3. Give your name and your phone’s IMEI.
  4. Pay your service provider on your next billing period (this depends on whether your network charges for this service).
  5. Wait for the unlock code.
  6. Insert a SIM card from another service provider into your phone.
  7. Upon opening your device, your phone will ask for an unlock code. Use the code your previous provider sent you.
  8. Press OK. Your phone is now good to go.

Method 2: Use Specialized Software (Best for Fast Unlocking)

This requires a third-party app and computer to unlock your phone. Under this method, you will need specialized software to change your phone’s program.

Before starting, remember that manually unlocking your phone through certain software can be risky and compromise your security.

  1. Find a GSM-unlocking software appropriate to your phone (the top options are available below).
  2. Download and run the app on a computer.
  3. Use a USB port to connect your phone to the computer.
  4. Follow the steps on the screen CAREFULLY.
  5. Test if your unlock is effective by inserting a GSM-supported SIM card into your phone.
  6. If successful, your phone should now be GSM-unlocked.

There are many SIM unlocking tools available for Android and Apple. However, finding a legitimate one is tricky.

📝 Take Note:

In some countries, software unlocking may be illegal due to SIM-lock laws that protect carriers' interests. Engaging in unauthorized unlocking could result in legal consequences.

Here are the apps that can help connect your phone to the computer:




Universal Advance Unlocker

This legacy software works with all versions of Windows, from 7 to 11. It unlocks devices like Alcatel, LG, Blackberry, Huawei, and Samsung, to name a few.


Dr. Fone

Dr. Fone is an all-in-one unlocking software that can recover data and manage files on your phone through a computer.



It is a one-click solution specialized for iPhones from 5S to the latest models using your macOS computer.

$29.99 to $34.99

This method requires caution as some software may contain viruses, and others necessitate rooting or jailbreaking your phone.

✅ Pro Tip:

Using specialized software for sim-unlocking can lead to data corruption or loss. Back up your files on an external drive or cloud storage before unlocking your phone.

Method 3: Unlocking through Hardware (Best for Business)

This method uses hardware to unlock a phone, functioning like software but directly connecting to the unlocker device rather than a computer.

Here are some popular tools you can use to GSM unlock your phone.




Sigma Box

This all-in-one box unlocks, flashes, and backs up 6,000+ phone brands.


Octopus Box

This unlocking tool works with Samsung, LG, Motorola, Huawei, HTC, and many more.

Starts at $59.99

Furious Gold

It works similarly to the other two boxes. It has 69 modules that let you work on various devices.


⚠️ Warning:

Going through your phone’s hardware can compromise your device’s functionality. It's recommended to find a technician to do this.

If you pay for a service, ensure they have the credentials to do it. A slight mistake can alter your phone. Meanwhile, warranty services do not usually cover such alterations you make to your device.

Method 4: Unlock via IMEI (Best for Fast and Safe Unlocking)

Third-party services, available through websites and apps, use your IMEI to change your phone's unlock status. These offer faster and more efficient options than service providers.

Here's a list of services you can consider:


Be wary of scams that claim to provide software unlocking services. Scammers may take your money without delivering the promised unlock. Some might even install different types of malicious software on your device, compromising your device's security.


A GSM-unlocked phone gives you more freedom in choosing the best SIM card for your device. Although it is safe to contact service providers, unlocking could take months. Utilizing software and hardware can be costly and hazardous. The ideal strategy for GSM unlocking is to rely on professionals.

GSM-unlocked phones are expensive but available for compatibility with other networks. Contacting service providers is safe, but unlocking may take months. Using software and hardware can be harmful and expensive. Trusting experts for GSM unlocking is the best approach.


Where can I have my phone unlocked?

You can find a local, independent shop nearby. On average, it costs $3 for Android phones and $20 to $60 for iPhones.

Can I just buy an unlocked phone?

Yes, but unlocked phones are usually more expensive than SIM-locked phones.

How long does it take to unlock a GSM phone?

Depending on your method, GSM-unlocking a phone can take 2 to 30 days.


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