Help an old man... 4G to 5G sim problem

[Craphouserat]

Hi

This week I upgraded from an iphone xr to an iphone 13. So i got a new 5G sim with the phone. I've put this in and done the sim swap thing but for some reason when I call my number it goes to voicemail.
I can make calls but when i do it comes up in the caller id section as my icloud address rather than my phone number.

Can anyone advise what I've done wrong or not done?

[Defcon5]

Sounds like your new SIM hasn’t been activated.

Put the old one in and see if that works

[Craphouserat]

Defcon5 said:

Sounds like your new SIM hasn’t been activated.

Put the old one in and see if that works

I can use whatsapp and i can make calls - when i do its my icloud address that comes up in caller id rather than my phone number.
I followed all the steps to activate my new 5g sim.

it's all really strange

[Defcon5]

Turn off the Wi-Fi and mobile data and try and call a landline or non-apple device to see what number shows up.