Cellular Apple Watch Ultra

[Ziggy2]

Hi

i have just purchased a Apple Watch ultra though 02 with a extra £5 per month data charge .

I am having problems using the watch standalone phone functions ( ie when my Apple phone is not with me ) 

if someone calls my number it just goes to answerphone on my actual phone abd doesn’t ring the watch .

All settings on watch and phone look ok but any ideas 

[MI5]

@Ziggy2 

Have you followed the setup routine here https://www.o2.co.uk/help/device-and-sim-support/apple-watch ?