Ring/voicemail

My Iphone 7 suddenly won't ring and goes to voicemail. People say that it'll ring for them, so it doesn't go straight to voicemail. But I don't get notification I have a voicemail (this has been an issue for several months) or a missed call . I've tried changing my voicemail message and it give me a the 1035 error. I've tried changing my voicemail password and it tells me 'Voicemail Unavailable". I've tried all the airplane mode, the DND mode, reset my phone, made sure ring is on, everything I've seen on here to try. It's still not working. Any suggestions of what else I can do? Or should I take it to a support center? I've had the phone less than a year, my carrier is StraightTalk. Any help or ideas would be greatly appreciated. Thanks