Have you tried shutting down the phone , removing the battery for 30 secs and rebooting?Sometimes the software can be confused and need a clean restart.
Do you have any call apps?
How many signal reception bars are there on your phone when you can not receive calls?
Can you call out?
Is your phone with factory settings or have you altered anything in its software?
This sounds as though it could be a network problem. Out of curiosity, what network are you on?
I suffered a similar problem (I'm on T-Mobile) and the phone struggled to switch between WiFi and GSM/WCDMA automatically. People who tried to call me were sent to my voicemail and I couldn't send or receive an MMS messsage without manually disabling WiFi and enabling mobile data.
I think this problem may have returned in some capacity as I have struggled to send and receive MMS and my location is displaying as United Kingdom rather than a specific town or city I am in.