Q: iPhone fails receiving calls and text messages

Hi everyone, here is my problem.

I have an iPhone 4 32GB. It was on iOs 5.1 (always worked perfectly) untill few days ago I have upgraded to iOs 7.1.

The problem after the upgrade is that phone calls or sms messages fails to be received. Strange thing is I can receive at times calls from cellphones, but I don't receive calls from land line numbers. And text messages arrive all at once after hours.

I have restored the phone in DFU mode twice, set up as new phone , tried a hard reset, network reset... nothing worked. It still fails to receive phone calls and sms messages.

Before you ask, the "don't disturb" is disabled.

I live in Italy and have a contract with TIM, i spoke with their cistomer service and according to them there's nothing more i can do on my end.

Any idea?

Thanks