How to activate a SIM card: A step-by-step guide

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). It's important to follow the right steps for your particular situation.  

The SIM card is the single most important piece of tech in your phone, because it's what lets you connect to a cellular or data network so you can actually use your phone away from Wi-Fi. So, while an activation may seem cumbersome, it’s crucial for enjoying your new phone or new service.

We put together this comprehensive, easy-to-follow guide that will help you activate almost any SIM card.  

How to activate a physical SIM card for Android and iPhone

Note: Beginning with the iPhone 14 in 2022, Apple has switched to eSIMs only in iPhones. If you have a 14 or later model, read about how to activate an eSIM on an iPhone.

1. Insert the SIM card in your phone

The first step is quite simple:  

1. Turn off your phone or put it 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 small hole near the tray. 

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). Some SIMs come packaged in plastic that lets you punch out the correct size of SIM card for your phone.

5. Slide the tray back in then turn on the phone or turn off Airplane Mode.  

2. Activate the SIM card with your carrier  

Most carriers will require that you activate the SIM card 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: AT&T, T-Mobile, and Verizon.  

How to 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 going 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.

How to 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.  

How to 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 going 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've completed your carrier activation steps, whether by talking to your carrier directly or simply following on-screen instructions, restart your phone by turning it off and back on. That lets the phone reset to 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 to be able to properly connect to the network.  

How to activate an eSIM for an iPhone or Android

1. Find your activation details  

After purchasing an eSIM, your carrier should provide you with 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.  

Activate eSIM on an iPhone  

1. Go to Settings -> Tap “Cellular.” 
2. Tap “Add eSIM.”  
3. Choose “Use QR Code” or “Enter Details Manually.” 
4. Scan the QR code or type in the details as provided by your carrier.  

Activate eSIM on an Android  

1. Go to Settings -> Tap “Networks & Internet.”  
2. Select “Mobile Network” -> “Add SIM.”  
3. Choose “Download a SIM instead.”  
4. 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 process.  

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) to configure the settings properly.  

5. Test out the connection  

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 (AT&T, T-Mobile, and Verizon) and lock you into a contract. Unlike cheap phone plan alternatives, these also tend to be the most expensive plans, up to $100 a month for one line.  

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. It's also the most common type of SIM used by international providers for affordable coverage while you're travelling.

Physical SIM vs. eSIM: Pros and cons  

Postpaid vs. prepaid SIM Card: Pros and cons

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

FAQs about activating SIM cards: