9 Simple Steps to Activate an AT&T SIM Card

Learn how to activate a physical or eSIM with AT&T

Co-authored by Gonzalo Martinez and Darlene Antonelli, MA

Last Updated: June 8, 2025 References

Did you get a new SIM card and need to activate it with AT&T? Activation is just a phone call away, as long as the person calling is an account owner or retail authorized user. A retail authorized user is a person who calls to activate your SIM when you go into a local AT&T store, and this often happens behind closed doors when you purchase a new phone. If you purchase a new phone from AT&T, the SIM card will be included and already activated, so you don't have to worry about this process! This wikiHow teaches you how to activate a new AT&T Wireless SIM card.

Things You Should Know

When you buy a new phone with AT&T, the SIM or eSIM is already set up and activated.
The easiest solution is to bring your phone to an AT&T store so they can find and input your SIM information.
Alternatively, use your IMEI, SIM card number, and call AT&T to activate the new SIM card.

Steps

Download Article

1
Locate and/or write down your IMEI number. This is a special code connected to your phone, typically printed and clearly labeled on the packaging. If you don't have access to this number, you can get it by dialing *#06# on the phone's keypad.^{[1]
X
Research source}
- If you have a phone that doesn't have a SIM slot, you have to get an eSIM. Go to https://m.att.com/myatt/native/deepLink.html?action=Overview&appInstall=N, sign in, scroll down to "My devices" and click Manage device next to the phone you're getting the eSIM for. Click Get new eSIM under "Options & settings." If you don't see the button to get a new eSIM, you already have one that's activated.
2
Locate and/or write down your SIM card number. This is also known as an ICCID number and is printed on the SIM card next to "ICCID."^{[2]
X
Research source}
- If you don't see "ICCID," it may be printed next to "CSN" or "EID."
- You can avoid having to try and find this information by going to a local AT&T store and they will take care of the process.
Advertisement
If you've already inserted the new SIM into your device, you can skip this and the next step.
4
Transfer a phone number from another provider (optional). If you're not transferring a phone number from another mobile provider (e.g., Verizon or T-Mobile), skip this step. If you are transferring a phone number, follow these steps to complete the transfer before you continue:
- Go to https://www.att.com/orders/checkmyorder in a browser.
- Enter the phone number you want to transfer and the billing ZIP code.
- Click Continue.
- Provide the requested information and follow the on-screen instructions to activate your card.
If you're not sure how to do this on your phone or tablet, visit AT&T's Device Support site in a web browser. Once you're there, select your model, click All Solutions, and then click Insert SIM Card for instructions.^{[3]
X
Research source}
You should also try using the mobile internet service without Wi-Fi enabled. If you are able to do these things, your SIM card is active, and you can start setting up your voicemail. If not, continue with this method.
Go to https://www.att.com/activations/ This opens the SIM card activation site.
The site will check your information and display instructions for your service and device.
9
Follow the on-screen instructions to activate the card. Once the SIM is active, you'll be able to place phone calls and use the internet.
- If you're unable to activate the card online, you can give AT&T a call from a working phone or visit an authorized AT&T store during regular business hours.
- AT&T support is available 24/7. If you're in the US, dial 1-800-331-0500. If you're outside of the US, dial 1-314-925-6925.^{[4]
  X
  Research source}
- When you try to activate your device with a carrier, you plug in your SIM card. It automatically syncs with your carrier.^{[5]
  X
  Expert Source
  
  Gonzalo Martinez
  Computer & Phone Repair Specialist
  
  Expert Interview}
- But sometimes there are apps, so the carrier might ask you for what SIM card you have. And instead of you using a tool to eject it, they'll show up as ICC ID settings.^{[6]
  X
  Expert Source
  
  Gonzalo Martinez
  Computer & Phone Repair Specialist
  
  Expert Interview}
- You can find the ICC ID number within Settings by tapping on General > About. If you scroll down, you can see it.^{[7]
  X
  Expert Source
  
  Gonzalo Martinez
  Computer & Phone Repair Specialist
  
  Expert Interview}

Community Q&A

Search

Add New Question

Question

What do I do when the phone I own was in a different state when it was owned by someone else?

Community Answer

The state it was activated in doesn't matter (unless it was in a different country). The cellular carrier is the only one that can unlock it for use on another carrier. Contact the cellular carrier for more info on how to activate on its network, or submit a request to unlock it for use on another cellular network.

Thanks! We're glad this was helpful.
Thank you for your feedback.
If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow
Yes No

Not Helpful 11 Helpful 4