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March 12, 2025

How to Activate a SIM Card: A Step-By-Step Guide

Written by Valeria

Getting a new phone or switching to a new phone service is an exciting upgrade, which also comes with the less exciting process of activating a new SIM card. Whether it’s an eSIM or a physical SIM card, the steps required to activate it vary slightly between carriers (and in some cases, between operating systems), which can make it confusing or even frustrating if the right steps aren’t followed.  

It’s important to remember, though, that the SIM card is the single most important piece of tech in your phone. It’s the key that unlocks your ability to connect to a cellular or data network, allowing you to actually use your phone away from Wi-Fi, freely. So, while an activation may seem cumbersome, it’s crucial for enjoying your new phone or new service, so we put together this comprehensive, easy-to-follow guide that will help you activate almost any SIM card.  

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How to activate a physical SIM card for iPhone and Android

1. Insert the SIM card in your phone  

The first step is quite simple, but if you’ve never had to insert a SIM card by yourself before, here is a step-by-step guide:  

  1. Turn off your phone first or turn on Airplane Mode.  

  2. Locate the SIM card tray (usually a notched-out slot on the side). 

  3. Take out the SIM card tray by inserting a SIM card ejector tool into the little hole. 

TextNow Tip: This tool is usually shipped out with a new phone, but if you don’t have one, you can also use an opened-up paperclip or the post of an earring.  

4. Insert your new SIM card into the tray (it’s cut out to match the shape of the card, so it’s impossible to put it in the wrong way!)

5. Slide the tray into the phone and turn it on or turn off Airplane Mode.  

2. Activate the SIM card with your carrier  

Most carriers will require that you activate the SIM card first before you’re able to use it. After you insert the SIM card into your phone, you may see that it connects to a network but you’re not able to get any service (the signal bars have an X over them), or that it struggles to connect to a network at all. In that case, you’d need to follow specific steps outlined by your carrier to complete the activation. Those prompts should be provided by the carrier with the shipment of the SIM card, but you can also follow these instructions for the activation steps required by the Big 3 networks: T-Mobile, Verizon, and AT&T.  

Activate a SIM Card from T-Mobile  

If you have a desktop computer or laptop, it’s recommended you follow these steps there, but if not, you can use your new phone – over Wi-Fi – to complete them as well.  

For a new T-Mobile customer:  

  1. After turning the phone back on, follow the on-screen setup prompts.  

  2. You can then either call 1-800-T-MOBILE to complete the process OR complete the process online by heading over to the T-Mobile account page:
    - Log into your T-Mobile account.
    - Select the line to activate the SIM card on (if you have multiple lines.).
    - Follow the steps to verify your account.
    - Enter your ICCID number (located in your device settings) to confirm the change. 

  3. Restart your phone to configure the new settings.  

For an existing T-Mobile customer: 

  1. Turn off SIM Protection (if it’s turned on). 

  2. After you insert the SIM card and turn your phone back on, the service should start working within a few minutes. If you’re having issues with signal or service, you can follow T-Mobile's troubleshooting steps.

TextNow Tip: SIM Protection is a security measure for preventing SIM Swap Scams. It's recommended you turn it on (if available) with your carrier with any new SIM card you activate.

Activate a SIM Card from Verizon  

If you have a desktop computer or laptop, it’s recommended you follow these steps there, but if not, you can use your new phone – over Wi-Fi – to complete them as well. 

For a new Verizon customer: 

  1. After turning the phone back on, follow the on-screen setup prompts.  

  2. You can then either call 1-877-807-4646 to complete the process OR complete the process online by heading over to the Verizon 'My Account’ page:
    - Log into your Verizon account.  
    - Select the ‘Activate or Switch Device’ page. 
    - Enter the required information, such as the ICCID number (located in your device settings), and IMEI (dial #06# on your phone’s keypad).  
    - Follow the steps to complete the activation.  

  3. Restart your phone to configure the new settings.  

For an existing Verizon customer: 

  1. Log in to your ‘My Account’ page on Verizon’s website.  

  2. Select the “Activate or Switch Device” page.  

  3. Complete the steps listed there to activate your new phone!.  

Activate a SIM Card from AT&T  

If you have a desktop computer or laptop, it’s recommended you follow these steps there, but if not, you can use your new phone – over Wi-Fi – to complete them as well. 

For a new AT&T customer: 

  1. After turning the phone back on, follow the on-screen setup prompts. 

  2. You can then either call 1-800-331-0500 to complete the process OR complete the process online by heading over to AT&T’s activations page:
    - Choose AT&T Wireless or AT&T Prepaid (if you have a prepaid SIM card) and follow the prompts to activate your device.  

  3. Restart your phone to configure the new settings. 

For an existing AT&T customer:  

  1. You can either call 1-800-331-0500 for customer assistance or activate your new phone online:
    - Log into your ‘My AT&T Account’ page.  
    - Select the line you're looking to activate the SIM card on, then choose “Manage device & features.”  
    - Update the SIM card number (the ICCID) and follow the on-screen instructions to complete the activation.  

  2. Restart your phone to configure the new settings.  

3. Restart your phone  

Once you completed your carrier activation steps, whether by talking to your carrier directly or simply following on-screen instructions, restarting your phone (turning it off and back on again) lets it reset the new configuration and connect successfully to the network.  

4. Test out the connection  

Even if everything looks good, and you see a network connection, you still want to test it out as soon as possible by making a call and trying to load a page on your mobile browser. Check that calls and texts go through, and that you have data access without Wi-Fi. If that’s not the case, contact your carrier for further troubleshooting steps, as some carriers may require you to change APN settings directly to be able to properly connect to the network.  

How to activate an eSIM for an iPhone and Android

1. Find your activation details  

After purchasing an eSIM, your carrier should provide you with the activation details, which will most likely be a QR code or an activation code.  

2. Enter the activation details into your phone’s settings  

An eSIM activation is fairly consistent across all devices, with some minor differences based on where you scan the QR code or enter the activation code.  

eSIM Activation on an iPhone  

  1. Go to Settings -> Tap “Cellular.” 

  1. Tap “Add eSIM.”  

  1. Choose “Use QR Code” or “Enter Details Manually.”  

  1. Scan the QR code or enter the details manually as provided by your carrier.  

eSIM Activation on an Android  

  1. Go to Settings -> Tap “Networks & Internet.”  

  1. Select “Mobile Network” -> “Add SIM.”  

  1. Choose “Download a SIM instead.”  

  1. Scan the QR code or enter the details manually as provided by your carrier. 

3. Follow the on-screen instructions 

Once you've entered activation details, follow the on-screen instructions to complete the activation.  

4. Restart your phone  

It may not be explicitly asked, but it’s recommended that you also restart your phone (turn it off and back on again) to configure the settings properly.  

5. Test out the connection  

Even if everything looks good, and you see a network connection, you still want to test it out as soon as possible by making a call and trying to load a page on your mobile browser. Check that calls and texts go through, and that you have data access without Wi-Fi. If that’s not the case, contact your carrier for further troubleshooting steps.  

Types of SIM Cards  

There are two main types of SIM cards: eSIM and physical SIM cards. In addition, cards differ based on whether they’re for a postpaid phone plan or a prepaid phone plan.  

A postpaid SIM card is used to activate a postpaid phone plan, which is a type of plan that bills you for service after the month ends. These are more commonly used by the Big 3 carriers (T-Mobile, Verizon, and AT&T) and lock you into a contract. Unlike cheap phone plan alternatives, these also tend to be the most expensive plans, running you up to $100 a month.  

A prepaid SIM card does the opposite. It allows users to pay for mobile services in advance, and as a result, lets you access much more affordable prepaid phone plan options.  

Physical SIM vs. eSIM: Pros and Cons  

Physical SIM Card
eSIM
Pros:
  • easy device switching.
  • can be used in different types of devices (tablets, smartwatches).
  • wide phone and carrier support.
 Pros:
  • can easily and quickly activate remotely without contacting customer support.
  • more secure: eSIMs can’t be stolen or swapped out of a phone.
  • ease of use for travel: can activate an international eSIM without having to purchase a physical card in store.
Cons:
  • not flexible for travel (if you need to switch out SIMs in the same device).
  • in most cases, involves contacting customer support for activation, which can be cumbersome.
  • Longer process for activation (either have to go to store to pick up SIM card or buy one online and wait for shipping).
 Cons:
  • Limited selection: not all phones or carriers support eSIMs.
  • No device switching: If your phone breaks or stops working, you can’t take out the SIM and insert it into another device to continue your service.

Postpaid vs. Prepaid SIM Card: Pros and Cons

Postpaid SIM Card
Prepaid SIM Card
Pros:
  • Access to premium networks with prioritized data.
  • More cost-effective for multiple line bundling.
  • Complementary perks (free subscriptions).
 Pros:
  • More affordable for a single line.
  • Flexibility. Without a contract, you are free to upgrade or switch plans and carriers as you see fit.
  • More choices (there are more prepaid plans than postpaid plans).
  • More accessible (no credit checks).
Cons:
  • Significantly higher monthly cost for a single line.
  • Locked to a contract.
  • A credit check may be required.
 Cons:
  • No network priority: Most of these plans have slower data speeds during times of congestion.
  • No perks
  • Majority of these plans offer lower data limits than postpaid phone plans.

If you have any questions or comments, send us a note at [email protected]! 

Frequently Asked Questions About Activating SIM Cards:

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