Why are my calls going straight to voicemail on my samsung galaxy grand prime?

[AC Question]

When someone tries to call me all calls are going straight to voicemail. I checked all settings and everything is turned on and there should be no reason my phone is not ringing when someone tries to call me. I tried restarting the phone, checking airplane mode, sound settings, device settings. The only thing i have not done is a factory data reset which I am hesitant about. Please help. Samsung Galaxy Grand Prime.