phone won't ring calls go straight to voice mail

Thanks! I fixed this on my partner's phone by having him call ##40# on his iPhone. Before that when anyone tried to call him it would just go straight to voicemail. Once it was working again, he tried calling code **61*18056377243**10# that someone else posted which is supposed to do the same but also let you change the number of seconds of ringing before it goes to voicemail (the last 2 digits in that code), but that made the straight to voicemail problem come back. So he called ##40# again which fixed it again.