Q: NO SIM Error - with the SIM already inserted and was in use.

I'm getting  ' NO SIM ' error past 3 days in my iPhone 5 .But I have been using the iphone with the current sim for past 5 months.

I used to reboot my phone to get the service back.

Is the problem with the SIM or with my iPhone?.  Do I need to reset my iPhone 5 thru itunes to get rid of this error..Please advise.