Wifi calling not working on new iPhone SE

[AM21]

Help please - I got a new iPhone SE yesterday (from O2) and set it all up, but there is no phone signal. I used to get only 1 bar but if it's 5G I won't get that yet. Ive checked my O2 account and wifi calling is enabled, but I can't turn it on on the phone. It just sends me back to my account. I was on hold for 25 minutes to O2 and the line disconnected...

[MI5]

@AM21 

You need to contact O2 to add iData to your account.
All numbers are in this guide Guide: Coronavirus Community Help and Support 
When you call, you will be asked for the reason you are calling.
Stay silent for 15 seconds and you will be taken to the keypad options.
Press 2 for Everything Else
Press 5 for More Options
Press 7 for Anything Else which will put you though to someone.
You can also try saying "Upgrade" or "Fraud" to be connected to an advisor.
8.00am is the best time to call if you can.

You can also switch off 5g in settings to get your 1 bar of 4g back.

[AM21]

Thank you so much! Actually I see it doesn't claim to have 5G, it's only saying 4G, so I am mystified as to why it isn't working.

Can I ask a really stupid question - which way up does the SIM card go? It has a cutout corner, so it looked like it would only go in face down, but perhaps I shouldn't have done that.

[MI5]

@AM21 

The cut out in the sim matches a cut out in the sim tray, so it will only sit flush one way round.

Make sure both cuts line up and you can't go wrong.

[AM21]

Thanks again.

[MI5]

You're welcome