mobile network not available with new sim

[ken3]

i have a new phone with a new sim but get 'mobile network not available' message so can't make calls.

everything else works. ... my old phone with the old sim still works. what have i not done?

[Edit: topic title clarified]

[MI5]

@ken3 

You need to put the old sim in the new phone.

[ken3]

its a different size

[MI5]

@ken3 

See if it pushes out to a smaller one:

If not, you need to do a sim swap Guide: Sim Swap: a mini guide 2017 update