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Sprint support pages are available for existing Sprint accounts here. If you are looking for more, visit our Migration Center.

The SIM card is your device's ticket to the T-Mobile network!


About SIM cards

  • Your SIM card is linked to your phone number, and it connects you to T-Mobile. It's not a memory card or SD card.
  • Your SIM card can be easily moved from your current phone into another compatible phone to transfer your service.
  • Check your device to find out the SIM size (See the "Tech specs" page), how to insert it, and how to set up SIM security.
  • T-Mobile devices support three SIM sizes. If your device needs a different size, see Buy a SIM card.
    • Nano SIM: The smallest SIM, most likely to be found in new devices.
    • Micro SIM: A medium SIM, normally used in previous model devices.
    • Standard SIM: The largest SIM, aka Mini SIM, found in older devices.
    • T-Mobile SIM cards comes with adapters to work in devices that require nano, micro, and standard SIMs.
  • Limited devices on our network support eSIMs using the T-Mobile eSIM app.
  • We strongly suggest that you change or update your  Customer PIN/Passcode to protect your account.


Buy a SIM card

T-Mobile SIM cards come with adapters, in case your device uses a nano, micro, or standard card.


Change or activate a SIM card

If you're using a device from another wireless provider, you first need to contact that provider to request a SIM unlock on the device.

To activate an unused T-Mobile SIM card:

  • Log in to or the T-Mobile app and click Account. Scroll down and click your device name to access the Activate or Change SIM option.
    • If your device type is listed as unknown (including BYOD devices), click View Account. In the account overview page, scroll down to Lines and Devices. Select the appropriate line and click Change SIM
    • This online option is available only to postpaid account.
  • Contact us or stop by a store. For your security, the account holder or an authorized user must make the request.
  • If you're changing to an eSIM on a postpaid account for a smartphone, your device will need to be connected to Wi-Fi and you'll need to use the QR code to download your eSIM settings.
  • If you want to activate an iPhone eSIM on a prepaid account, download the T-Mobile eSIM app.


SIM card and PUK errors

'PUK Lock' or 'SIM Lock' errors

If a SIM PIN security code has been entered incorrectly multiple times, the SIM will lock and require you to enter a PUK code to use your device again.

  • Be careful!
    • If you incorrectly enter your PUK code 10 times, your SIM will need to be replaced.
    • Moving your SIM to another device will not fix this error.
  • The PUK is unique to your SIM card. To get the code, you need to either:
    • Contact us online or with another phone. For your security, you must be the account holder or authorized user to verify.
    • Use the PUK Code printed on the card your SIM came in. Make sure the SIM card number matches the card.
  • Once you have the PUK code, follow the instructions for your Device to enter it.
Other SIM errors
  • "Contact your service provider'
  • 'Insert SIM' or 'Invalid SIM'
  • 'Unregistered SIM'

If you receive any of these errors:

  1. If using a non-T-Mobile device, make sure the SIM is unlocked. Contact the original provider if you need help.
  2. Turn off the device.
  3. Remove the SIM card from the device. For steps on how, visit the Devices page.
  4. Re-insert the SIM card snugly in the SIM slot.
  5. Turn on the device.
  6. If you're able to register on our network, the error should no longer appear.
  7. Perform a manual network selection and try to register on the T-Mobile network.
  8. If available, move the SIM card to another T-Mobile device and test to see if it works. This test will help Customer Care diagnose the problem.
  9. If the error continues, use another device or online option to contact us.

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