Cannot activate new iPhone 12

[LadyClementine]

Hello
I received my new iPhone 12. I followed all instructions to transfer from my iPhone SE but it seems to have failed. I cannot make calls from new phone or send messages etc. My old phone is still on the network and my new phone isn’t. What do I need to do?

[MI5 · Accepted solution]

@LadyClementine 

You need to use your old sim or do a sim swap if you want to use the new one Guide: Sim Swap: a mini guide 2017 update 

[LadyClementine]

I was sent a new sim which I put in. Was that wrong?

[MI5]

@LadyClementine 

The new sim is for 5g so you only need to use it if you are in a 5g area currently.

If not, you just use your old sim.

[LadyClementine]

It’s okay, I’ve done it! Thank you so much. I’m such a technophobe! Haha!

[MI5]

No problem at all. Enjoy your new phone.