No voicemail notification icon


Please help, anyone..
I have a dual SIM Samsung Galaxy J7 Prime. I've never been able to get voicemail icons to show in the notification bar. So I don't know if I have a voicemail. (I do get missed call notification icons, and the missed number will show the little icon of there's a message, but I routinelymiss seeing that.)
I've tried to find a fix in settings, voicemail settings, call settings, notifications, application manager, even dialing into my voicemail to try turning notifications on or off. There is no such option. I'm about to look for an app for voicemails since this has been so illusive. But any help offered here would be great!