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  • Three_Sheena
  • 16-10-2015
  • 17550
  • 0

How to Activate a New SIM Card

by on ‎16-10-2015 12:54 PM - last edited on ‎06-03-2018 04:08 PM by 3 Community Manager (17,550 Views)

Activate your SIM.jpg


Whether you need a new SIM due to issues you’re facing, or you’ve lost your SIM card, activating your new SIM card on Three couldn’t be simpler. Pick up a free replacement SIM in any Three store and go online to activate your new SIM card -


You'll need the long serial number from the SIM card packaging, this will begin with 89 353.


If something goes wrong or the SIM hasn't activated in 24 hours, we may need to activate it manually. 

If it's between the hours of 7am - 11pm, Monday to Sunday, click here to activate the SIM card with our Webchat team.


Outside of these hours, send us a PM and include the SIM card serial number. Please do not post this info publicly. We will get back to you via private message within 24 hours to confirm that it's going through.


You'll still have service on your old SIM, until the new SIM is active. In some cases when the service on your old SIM drops, you'll need to restart the phone with the new SIM in it.


Feel free to get in touch if you have any feedback on this, or need any help.

by seankwalsh
on ‎28-06-2017 10:54 AM

I am trying to activate a new sim card and have put in all the details but keep getting a message saying

"You must enter a SIM number beginning with undefined"

What does undefined mean ?

on ‎28-06-2017 11:42 AM

Hi @seankwalsh, are you enter the SIM number that starts with 89353?  You can activate a replacement SIM at the link here:


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