Thanks for posting on the Forum. I'm sorry that you aren't receiving calls on your Nexus 4 mobile. Have you tried the handset factory reset that J0hn advised to try? Is this now working for you?
If you are still not receiving incoming calls, I can check this for you, but I'll need to take more information. I'll send you a private message requesting further details. Just check the envelope icon at the top right of this page.
Need help changing SIM card? Find out more about activating your 4G ready SIM. 4G SIM Swap Help