If you're new to O2, your sim is ready to use straightaway. Just pop it in your device and you're good to go. If you're new to O2 and you have a Pay As You Go sim, you'll need to top up to activate it. If you're already an O2 customer and you've upgraded your device, you might need a different sized sim.
Quick steps: Activating a new SIMInsert the new SIM into your phone, and have the phone turned on.Activate your new SIM card by using its accompanying activation key (this will be included in the package). ... Use this key to activate the SIM card online. ... Wait some time, and it should be activated shortly.Oct 2, 2020
Even if the SIM card is pre-activated, you may find better rates on the carrier's website. Activating or registering the card online lets you select special packages which can benefit heavy international users or heavy text users, for instance.
After doing this it can take up to 24 hours but is generally quicker. The service will stop on your original sim card and then the process will start to transfer your number & Tariff to the new sized sim card. Keep turning your phone off and on with the new sim card in it to help the process. You're very welcome.