Hi @RobinHam
Are you in the UK or are you abroad at the moment?
If abroad, which country are you in?
Have you tried a manual network selection to another network?
If you're in the UK head over to our Check Coverage and Signal in Your Area - EE page to check coverage and any issues in the area, where you can also report the issues you're having, which the engineers will check and get back to you.
You can also have a look at our Mobile Signal Problems | Mobile Help page which has some useful information.
It's worth testing your SIM card in a different device if you have access to one, just to rule out any handset faults.
Ali
