What was O2 Mobile network previously known as?

Question

T Mobile was called "one to one". What was O2 called?

Answer 1

as above.LoL

Answer 2

Cell-Net

then BT Cellnet

then 02.

Answer 3

BT CELLNET

Answer 4

BT cellnet 02 also own Three network as well  

Answer 5

BT mobile

Answer 6

it was called bt cellnet

Answer 7

BT CELLNET, like if you put your O2 sim in an old phone, on the screen it will say BT CELLNET rather than O2. It shows this on my Nokia 3210 (yeah I still have it, gotta love the brick!! Lol).