SIM card: what it is, how to remove, install, in an iPhone

SIM card: what it is, how to remove, install, in an iPhone

SIM cards are so thoroughly integrated into our everyday lives that we don't pay attention to them anymore and do not understand what they are used for. In this article, we dig into the concept of SIM cards and eSIM, explain how to activate SIM cards, insert and remove SIM cards, and deal with not working SIM cards, etc. Read on!

What is a SIM card used for?

A SIM card, or a subscriber identity module/subscriber identification module, is a tiny memory card that contains unique information and is linked to a particular network carrier. What does a SIM card do? Users can install a SIM card into their phones and tablets, make calls, write SMS, and use cellular data to access the Internet. Without a SIM card, users can still use WiFi and surf the web, take photos and videos and use other mobile devices' features, but text messages and calls won't be available. SIM cards also contain a small amount of memory that can hold about 250 phone contacts and some text messages. 

What is a prepaid SIM card?

A prepaid SIM card is one without preloaded credit, such as an international SIM card. You can top up your credit balance with the service provider from time to time and use it occasionally. This type of SIM card is particularly handy for traveling. 

What does a SIM card look like?

The SIM card looks like a tiny piece of plastic with a microchip. The chip contains a unique identification number, a phone number, and other specific to the user data.

There are several types of SIM cards:

  • Full SIM: 85 mm x 53 mm
  • Mini-SIM: 25 mm x 15 mm
  • Micro-SIM: 15 mm x 12 mm
  • Nano-SIM: 12.3 mm x 8.8 mm
  • Embedded SIM: 6 mm x 5 mm

iPhone 5 and up and Samsung Galaxy S6 and S7 use the Nano-SIM. Samsung Galaxy 4 and 5 use Micro-SIM instead. It's important to know that the size of a SIM card doesn't influence its characteristics, such as its memory or data included. 

How to activate a SIM card?

  • How to activate an AT&T SIM card?

To activate an AT&T SIM card, insert it into your device, switch it on and follow the onscreen instructions. You can learn where is your SIM slot via a Device Support manual on the AT&T website.

  • How to activate a Verizon SIM card?

If you are wondering, "how do I activate a new Verizon SIM card," don't worry; we've got you covered. Here's how to do it. 

Go to Activate or Switch Device section on and enter your new SIM card number. This will add the SIM card details to your account. Next, insert the SIM card into your device. 

  • How to activate a Straight Talk Byop SIM card?

Go to, enter your Service Card PIN, and follow the onscreen instructions. You can also call 1-855-222-2355 and activate it with the help of an operator.

  • How to activate a T-Mobile SIM card?

Insert your SIM card into your phone when it is switched off. Next, turn your phone on and follow the on-screen instructions. Finally, call 1-800-T-MOBILE to finalize the process. You can also activate your new T-Mobile SIM card online. 

  1. Go to the T-Mobile website, log in to your account, or create a new one.
  2. Follow the onscreen prompts to verify your account.
  3. Enter your ICCID number to complete the process.
  • How to activate a Google FI SIM card?
  1. Insert your SIM card into your mobile device.
  2. Open and enter the code from the packaging of your SIM card.
  3. Perform a setup: 

For Android devices: Go to Settings > Network & Internet > Mobile Network > Advanced > Access Point Names. Tap More > Name and enter Google Fi. Tap APN and enter h2g2. Go back to the previous page and select Google Fi. If the setup was successful, you'd see Fi Network/Google Fi/T-Mobile at the top of your screen.

For iPhone/iPad: Go to Settings > Cellular > Cellular Data Network. For Cellular Data APN, enter h2g2.​​​​​​​

  • How to activate a Boost Mobile SIM card?
  1. ​​​​​​​Insert your physical SIM card into your phone and switch it on.
  2. Go to and click on Activate SIM card.
  3. Then, enter your SIM serial number from the back of your SIM pack and follow the onscreen instructions.

How to insert and remove a SIM card?

  • How to remove and insert a SIM card on an Android device (e.g., Samsung Galaxy S6 and newer)?

If you want to take your SIM card out of your iPhone, turn off your phone and insert the SIM-eject tool (or a simple paperclip) into the small hole next to the SIM tray. Gently push it until the tray pops up. Then, slide the tray out from the device and remove the SIM card by simply lifting it. To insert a SIM card, place it into the tray with the notch on the SIM card aligned with the notch on the tray, then reinsert the tray. 

  • How to remove and insert a SIM card on an iPhone? 

Insert a paper clip or a SIM-eject tool into the hole beside the tray. Push it towards your iPhone, and it will pop out. Remove or insert a SIM card and close the tray. 

Where is a SIM card slot on iPhone 14?

If you have purchased an iPhone 14 in the United States, your iPhone doesn't have a SIM tray. You can learn how to set an eSIM on your new iPhone here.

What to do if a SIM card is not working?

If your SIM card is not working correctly: the screen shows that the SIM card is not installed or shows the error message "SIM card busy. Try later" (which happens on Samsung Galaxy S21 often), don't worry, there is a way to fix the issue.

  1. Switch to Airplane mode and restart your phone.
  2. If it doesn't help, remove the SIM card, gently clean it and reinstall it.
  3. Try the same SIM card on another device.
  4. If none of this works for you, contact your carrier and order a new SIM card or switch to an eSIM.

What is a virtual SIM card & how to get one?

An eSIM is an innovative industry-standard digital SIM that authorizes you to activate a cellular plan from your carrier without using a physical SIM. You can install multiple eSIMs on your phone (eSIM works with the latest phone models), and use various phone numbers switching from one plan to another. This comes in handy if you travel a lot and don't want to spend too much money on roaming: the solution is to install an eSIM and use it together with your regular phone number. 

any more questions about SIM cards? check out our forum!