What type of SIM is O2 using?

[evantkh]

As title, what type of SIM is O2 using? USIM? ISIM? or something else?

[Beenherebefore]

Why ?

[Anonymous]

It's a SIM card. 

[viridis]

What did giff gaff community say?

[evantkh]

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@viridis wrote:
What did giff gaff community say?

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I don't see an answer as well.

[evantkh]

I am actually seeing a ridiculous problem like this.

Both SIMs are LTE ready, tested with Galaxy Note 3 at the same place.

In my Chinese phone, the left one is O2 SIM, the right one is giffgaff SIM.

[evantkh]

Actually, I think this is the problem of the device firmware design, not working well with MVNO.