on 20-09-2016 13:20
Im planning on buying a phone from o2, do i need to use the sim card it comes with(because it tells me i need to choose a tariff) or can i use my current giffgaff sim. (giffgaff sims work on o2 locked phones)
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on 20-09-2016 13:22
OnePlus 6 (O2 & Sfr), Z3 Tablet (Three UK), iPhone 8+ (EE)
20-09-2016 22:32 - edited 20-09-2016 22:33
I think you need to use the SIM it comes with to unlock your device under that account if you may use SIMs of other carriers. If you will certainly use giffgaff only, usually it should still work well without unlocking the device.