Is this a new connection or a replacement SIM @AA48 ?
If new, you might need customer services to activate it - call them on 202 or 0344 809 0202 if pay monthly, or 4445 or 0344 809 222 if PAYG (or use 0800 032 1402 if you have no other line, and you can use Skype for free - Guide: A Guide to Skype ).
Alternatively you can message on social media:
Facebook ( https://o2uk.co/O2CFB) , Twitter ( https://o2uk.co/O2CTW) or Instagram ( https://o2uk.co/O2CIG)
If a replacement for a lost/stolen sim, then you need to contact customer services to remove ALL of the bars on the account.
If you are moving a number from another network then it might take a while (and several off/on cycles) of your phone to get everything working.
Finally if none of that is true, see if these help:
Guide: How can I sort out my network issues?
Guide: Is the network down for me or everyone?
Please note, this is not customer services and we cannot access your account. Do not publish personal details (email, phone number, bank account).
Link to our guide on how to contact them can be found here
