set up your AT&T SIM card online, by phone, or in an AT&T store

AT&T SIM card set up is straightforward and takes about 15 minutes. You can start the process online at att.com/set up, call AT&T at 611 from any phone, or walk into an AT&T retail location. The method you choose depends on whether you have an existing AT&T account, are switching from another carrier, or are starting service for the first time.

Before you begin, have your SIM card number ready — it's printed on the card itself and also on the packaging. You'll also need a valid payment method and a phone number you want to use. If you're bringing a number from another carrier, AT&T can port it during set up, though this usually takes a few hours to complete.

Key Takeaways

  • You can set up online at att.com/set up, by phone at 611, or in an AT&T store; online set up is fastest if you already have an AT&T account.
  • Have your SIM card number, a valid payment method, and your desired phone number ready before you start.
  • If you're transferring a number from another carrier, AT&T can port it during set up, though the transfer typically takes a few hours.
  • After set up completes, insert the SIM card into your phone and restart it; service usually begins within minutes.
  • If set up fails, check that your phone is unlocked and compatible with AT&T's network, then contact AT&T support to troubleshoot.

Online set up through AT&T's website

The fastest route for most people is att.com/set up. The site walks you through a series of screens: first it asks whether you're a new customer or an existing account holder. If you already have AT&T service, you can add the new SIM to your current account in a few clicks. If you're new, you'll set up a login and billing address.

Next, you'll enter your SIM card number and choose your phone number. AT&T shows you available numbers in your area code, or you can port an existing number from another carrier. If you port, AT&T asks for your account number and PIN from your old carrier — you can find these on your old carrier's bill or by calling their customer service. The port request processes in the background while your new SIM activates.

Once you confirm your payment method and review the plan details, AT&T sends a confirmation email. At this point, your SIM is active. You can insert it into your phone when ready, though if you're porting a number, that number won't ring on your new phone until the port completes — usually within a few hours, sometimes up to 24 hours.

Phone set up by calling 611

If you prefer to speak with someone, call 611 from any phone. An AT&T representative will ask for your SIM card number, desired phone number, and billing information. This method works well if you have questions about plans or need help choosing a number, but it takes longer than online set up — typically 20 to 30 minutes including hold time.

The representative can also handle number porting during the call. They'll ask for your old carrier's account number and PIN, then submit the port request. Like online set up, the actual number transfer happens in the background and can take several hours.

In-store set up at AT&T retail locations

AT&T stores can set up your SIM while you wait. Bring your SIM card, a valid ID, and your payment method. A store associate will enter your information into their system, assign you a phone number or port your existing one, and hand you an activated SIM card. This is useful if you want to test your phone's connection before leaving, or if you need help inserting the SIM or setting up your device.

Store set up takes about 15 to 20 minutes. If you're porting a number, the associate will explain that the transfer happens after you leave — your new number will ring on your AT&T phone once the port completes, which is usually the same day but can take up to 24 hours.

What happens after set up is complete

Once AT&T confirms your set up, insert the SIM card into your phone's SIM slot (usually on the side or back of the device). Power off the phone, insert the SIM, and power it back on. Within a minute or two, your phone should show AT&T's network name and full signal bars. Send a test text or make a short call to confirm service is working.

If you ported a number, that number won't ring until the port completes. During the waiting period, calls to your old number may still ring on your old phone. Once the port finishes, your old number will ring only on your AT&T phone, and your old carrier's service will stop.

Troubleshooting set up problems

If your phone doesn't show service after set up, first check that your phone is unlocked — meaning it's not restricted to a single carrier. If you bought the phone from another carrier and haven't unlocked it yet, AT&T service won't work. Contact your old carrier to request an unlock code, then enter it into your phone's settings.

Next, confirm your phone is compatible with AT&T's network. AT&T uses both 4G LTE and 5G frequencies; older phones may support only 4G. Check your phone's manual or AT&T's compatibility tool at att.com to verify. If your phone is locked or incompatible, you'll need to resolve that before service will work.

If your phone is unlocked and compatible but still shows no service, restart it completely — power off, wait 30 seconds, and power back on. If that doesn't work, contact AT&T at 611 or visit an AT&T store. A representative can check whether your SIM activated correctly and troubleshoot network connection issues.

Porting your number from another carrier

AT&T can port your existing phone number during set up at no extra charge. You'll need your account number and PIN from your old carrier. These appear on your bill, or you can call your old carrier's customer service to request them.

The port request submits when you complete set up, but the actual transfer takes time. AT&T typically completes ports within a few hours, though some take up to 24 hours. During this window, calls to your old number may ring on both your old phone and your new AT&T phone. Once the port finishes, your old number rings only on AT&T, and your old carrier stops providing service.

If your old carrier charges an early termination fee, that's a separate issue from the port itself. AT&T doesn't pay those fees, so you may owe your old carrier money even after your number moves to AT&T. Check your old carrier's contract or call them to understand any fees before you port.

Frequently Asked Questions

Can I set up a SIM card without an AT&T account?

Yes. If you're new to AT&T, the set up process creates an account for you. You'll need a valid payment method and billing address, but you don't need to have been an AT&T customer before. Online set up at att.com/set up or a phone call to 611 both work for new customers.

How long does it take for a ported number to work?

Most ports complete within a few hours, but AT&T allows up to 24 hours. During the waiting period, your old number may ring on both phones. Once the port finishes, your old number rings only on your AT&T phone. If it takes longer than 24 hours, contact AT&T to check the port status.

What if my phone doesn't recognize the SIM card after I insert it?

First, power off your phone, remove the SIM, and reinsert it firmly. Power back on and wait a minute. If your phone still doesn't recognize it, check that your phone is unlocked and compatible with AT&T's network. If both are true, contact AT&T at 611 — the SIM itself may be defective or your account may not have activated correctly.

Do I need to do anything special if I'm switching from another carrier?

Tell your old carrier you're leaving so they can close your account and stop billing you. Request an unlock code if your phone is locked to them. During AT&T set up, port your number if you want to keep it. After the port completes, your old carrier's service stops automatically.

Can I set up a SIM card for someone else?

AT&T requires the person whose name appears on the account to complete set up or be present in the store. If you're activating for a family member, they'll need to provide their ID and payment method, or authorize you in writing. Call 611 or visit a store to ask about authorization options.