No data

[Dom9]

Help

[Dom9]

I have no signal or data. I have switched my phone on and off

[Enlli]

Not a lot to go on.

Are your payments up to date?

If you do a manual network search do you see other networks?

Guide: Is the network down for me or everyone? 

Guide: How can I sort out my network issues? 

If you need to contact O2

Guide: How to find help & contact O2 

[Oxonian]

This app is mentioned in the guides that you @Dom9 have been referred to, but in case you missed it, this is really useful :-

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.

[japitts]

If you have no signal, there's your answer. You can't use voice, text or data without signal (WiFi-excepted)

If you have signal but can't use data, that's a different issue.