Go to your 'calling history' file. If you show the call as 'outgoing', it is YOU calling the default callback number to access / retrieve your voicemail messages. If you show the call as 'incoming', it is a number that is being spoofed by a hacker or robocaller computer. Don't sweat the 'outgoing' events and block the 'incoming' ones.
Had several calls from this 832-494-9000 listed on my cell, no messages. I don't keep my phone on at all times, guessing they called when it was off. Had no idea till I saw the number today as incoming call, then looked at history and had several calls listed.
I got a call about 7 a.m. It went to voicemail. When I listened to the message, all I heard was music in the background. Hmm. Probably a bored teenager.
Left voicemails on my phone 5 times. I don't dare answer it, no telling what it is. Didn't listen to the voicemails, either, because no one I know has that number. The 832 area code makes me suspicious, and I have also gotten several 866 area code numbers this week, too. It seems that if I reject one number on my cell, they switch to another number, which seems fishy to me, I think they are going through alist of some kind.