Just wondered if it was just me?
I cannot call anyone and incoming calls go straight to voicemail.
I can get through to voicemail but only after a long'ish wait.
Profile / account / iphone all seem ok.
Phone has been rebooted.
O2 don't report any service issues.
Has the SIM been working OK until very recently and stopped working unexpectedly, or has it never worked since activating the SIM?
Do texts (in and out) and mobile data work OK?
Are you currently in the UK?
Please test dial the following numbers, and say exactly what you hear for each of them: