mobile network not working

[craigharley]

Mobile network is not working. It only says "emergency calls only"

Can I have a replacement sim?

[Enlli]

How do you know it's the SIM

Have you done a network search to see if the phone can see alternate networks?

Have a look at these guides

Guide: Is the network down for me or everyone? 

Guide: How can I sort out my network issues? 

[Oxonian]

This app might shed further light on your problem @craigharley :-

My Network App - Find Out More About Your Network Coverage | Apps | O2

https://www.o2.co.uk/apps/my-network

Understand your network coverage

With the My Network app you can keep an eye on your coverage, wherever you are. Download the app and you’ll be able to:

- check the status of our network in your area – you don’t even need to enter your postcode
- test your network speeds
- report any issues with your service.

It’s simple to use and means that you can check the network without having to visit the main site or even enter a postcode.