How to Clone a SIM Card for Two Phones: A 2025 Guide (Methods That Work)

Is It Possible (and Legal) to Clone a SIM Card?

Before we dive into the "how-to," let's address the elephant in the room: Can you actually clone a modern SIM card yourself?

To understand this, we need to look at the tech inside your plastic chip. SIM cards have evolved significantly:

• COMP128v1: This is the "old school" version. It is the only version that can be cracked and cloned using cheap hardware readers.
• COMP128v2, v3, & USIM (4G/5G): These modern cards utilize advanced encryption. Their "Ki" (authentication key) cannot be calculated by standard software, making them virtually impossible to clone at home.

The Verdict: If you bought your SIM card in the last 10 years, you likely cannot "hack" it manually. Trying to do so might trigger your carrier's security algorithms, permanently locking your original SIM.

However, just because you can't hack it doesn't mean you can't duplicate the service.

If you're switching to a new phone as part of this process, managing your data can be a challenge. A tool like Dr.Fone Basic can help you seamlessly transfer contacts, photos, and files.

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Method 1: Using Carrier Multi-SIM & eSIM (The "Legal" Clone)

If you want to use one number on two phones reliably in 2025, you shouldn't be looking at card readers—you should be looking at Multi-SIM or Number Share services.

Most major carriers in the US, UK, and Europe now offer this feature legally. It allows you to have a primary SIM in your main phone and a secondary SIM (or eSIM) in another device (like a secondary phone or smartwatch) that shares the same number and data plan.

How to set it up:

• Step 1: Contact your Carrier: Ask for services like "T-Mobile DIGITS," "Verizon Number Share," "AT&T NumberSync," or "Vodafone OneNumber".
• Step 2: Request a Secondary SIM/eSIM: They will provide a new physical card or a QR code for an eSIM.
• Step 3: Activation: Once inserted, the network links the unique ID of the new card to your existing phone number.

Method 2: The Traditional SIM Cloning Process (For Older SIMs)

If you have a very old SIM card and want to try the DIY approach, the logic involves extracting the IMSI (International Mobile Subscriber Identity) and the Ki (Authentication Key) from the original card and writing them onto a "blank" wafer card.

First, I will show you what you will need to start with the duplication:

• A SIM Card Reader/Writer (you can purchase it online).
• A Blank Programmable SIM Card (often called a "Wafer").
• Download and Install MagicSIM: this software will help you to copy the SIM card. https://ssl-download.cnet.com/MagicSIM/3000-2094_4-10601728.html

Follow the next tutorial to duplicate SIM:

• Step 1: Extract the Key Remove the SIM from your phone and insert it into the USB Card Reader. Connect it to your PC. Open your MagicSIM software and select "Read from SIM".
• Step 2: Crack the SIM In the software toolbar, select "Crack" > "Strong Mode" > "Start".

Warning: This process attacks the SIM card to find the key. It can take hours. If interrupted, the SIM may be corrupted.

• Step 3: Save the Data Once the software successfully calculates the Ki code, it will generate a .dat file. Click File > Save As to store this strictly confidential data on your computer.
• Step 4: Write to the Blank SIM Remove your original SIM and insert the Blank Wafer. In the software, click "Connect" and then "Write to SIM." Select the .dat file you just saved.
• Step 5: Finalize The software will ask for a security code (usually provided with the blank card). Once entered, the write process finishes. You now have a physical clone.

Information: To extract the KI code, you can choose to download the XSIM software on your computer too. Once executed, you will only have to wait for your reader to detect and verify that the SIM is inserted in the reader. XSIM will be in charge of locating the IMSI inside the SIM card and will show it directly on the principal screen.

Ki extraction can be complicated because it is a secret key that each SIM possesses. It has a length of 16 Bytes (16 numbers from 0 to 255). This makes 2 ^ 128 possible combinations of that number, and its extraction can take 8 hours. Once done the same, we will be in a position to duplicate our SIM.

Beyond the Signal - Cloning Your Phone's Data

Getting the "signal" on two phones is only half the battle. The biggest frustration users face when setting up a second phone is that it feels empty. Your photos, WhatsApp chats, contacts, and call logs are still on the old phone.

You don't just want to clone the SIM; you want to clone the experience.

This is where Wondershare Dr.Fone - Phone Transfer becomes essential. While your carrier handles the phone number, Dr.Fone handles the digital soul of your device.

Why Dr.Fone is the perfect companion for dual-phone users:

Cross-Platform Cloning: Moving from an iPhone to a secondary Android? Or Android to Android? Dr.Fone bridges the gap seamlessly.

• 1-Click Switch: It’s not just about contacts. You can transfer photos, videos, call logs, calendar events, and even apps in a single click.
• Security First: Unlike cloud backups which can be hacked, Dr.Fone transfers data directly from device to device using a secure connection.
• No Overwriting: The software intelligently merges data, so you don't lose existing files on the target device.

Dr.Fone - Phone Transfer

1-Click Phone-to-Phone Transfer

• Easy, fast, and safe.
• Move data between devices with different operating systems, i.e., iOS to Android.
• Supports iOS devices that run the latest iOS version
• Transfer photos, text messages, contacts, notes, and many other file types.
• Supports over 8000+ Android devices. Works for all models of iPhone, iPad, and iPod.

Available on: Windows Mac

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Step-by-Step: How to Clone Phone Data with Dr.Fone

Ready to make your second phone a true duplicate of your first? Follow these steps:

• Step 1: Launch Dr.Fone
  Download and install Dr.Fone on your computer. Open the toolbox and select "Toolbox" > "Phone Transfer" from the main dashboard.

• Step 2: Connect Both Devices
  Connect both your "Source" phone (the old one) and your "Destination" phone (the new one) to the PC via USB. Dr.Fone will automatically detect them.
  Note: You can click the "Flip" button if the Source and Destination are in the wrong order.

• Step 3: Select Files to Clone
  Check the boxes for the data you want to copy (Contacts, Messages, Photos, Call History, etc.).
• Step 4: Start Transfer
  Click "Start Transfer". Keep both phones connected until the process is complete. In just a few minutes, your second phone will have all the essential data from your main device.

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Comparison: Which "Cloning" Method is Right for You?

To help you decide, here is a quick comparison of the three methods discussed in this guide.

Conclusion

In 2025, the concept of "SIM cloning" has changed. The days of buying a cheap card reader to hack a SIM card are effectively over due to modern encryption standards. If your goal is to use one number on two phones, the only reliable and legal path is contacting your carrier for a Multi-SIM or Number Share service.

However, getting the signal is only half the battle. To truly "clone" your experience, you need your data to move with you. This is where Dr.Fone - Phone Transfer bridges the gap, allowing you to replicate your contacts, photos, and history onto your second device instantly. By combining a Carrier Multi-SIM plan with Dr.Fone's data transfer, you get the perfect dual-phone setup without the technical headaches.

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FAQs

1. Is it illegal to clone a SIM card?

It depends on the intent. Cloning your own SIM card for personal convenience was historically a grey area, but cloning someone else's SIM card is strictly illegal and constitutes identity theft. Furthermore, attempting to clone modern SIMs often violates your network carrier's Terms of Service, which can lead to a permanent ban.

2. Can you clone a modern 4G or 5G SIM card?

Practically speaking, no. Modern SIM cards (USIM) use COMP128v2 and v3 encryption algorithms. Unlike the older v1 cards from the early 2000s, these new cards have security keys (Ki) that cannot be extracted by standard consumer card readers. Attempting to crack them usually results in the card "self-destructing" (locking itself) to prevent theft.

3. What are the risks of using a cloned SIM card?

If you successfully clone a SIM (using the old method) and turn both phones on simultaneously, the network will detect two devices with the same IMSI attempting to register. This immediately flags a security alert, causing the carrier to block both the original and the cloned SIM to prevent fraud.

4. eSIM vs. Multi-SIM: Which one is better for me?

They are not mutually exclusive! Multi-SIM is the service that allows one number on two devices. eSIM is the technology that allows you to activate that service without a physical card. For a secondary phone, using an eSIM is generally better as it allows you to activate the second line instantly via a QR code sent by your carrier.

Dr.Fone App - Phone to Phone

Wireless Transfer: Cross-Platform Transmission Between iOS and Android Devices

• Supports photos, videos, music, files, and contacts.
• Rapid transfer with visual data display.
• One connection for multiple transfers.
• No mobile data or cables needed.

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