I had this problem too. I too switched sim cards, but then had the problem briefly again. A restart helped.
I was talking to Samsung support about another issue, and mentioned the dialing issue. They suggest I go to the three phone applications, clear cache, then force stop and restart the phone.
Is the phone turned on???
Just kidding - I couldn't resist. I used to work in a call center supporting wireless customers and once I had a customer with the exact same problem. After doing a lot of troubleshooting on her account (I spent far too long on it, much to my chagrin) I realized that she just didn't have the phone turned on. No wonder it wouldn't ring....