No signal

[Nik8]

I have no signal 

[Bambino]

@Nik8 See these guides:

How can I sort out my network issues? - o2uk

Why do I have poor coverage indoors? (o2.co.uk)

Wifi and 4G Calling explained | O2

[Oxonian]

@Nik8 

This might also be worth considering :-

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

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