quick google bring up these suggestions, hopefully one of them helps.
access the voicemail application, select the menu icon, and select Settings. From the next screen, please ensure "Use notification settings for voicemail notifications" is checked
To access the “Show notifications” setting in your voicemail application you need to access your cell phones
Settings, find and open the
Application manager (sometimes located under the “More” tab on many Android smartphones), make sure that all of the apps are showing (you may need to scroll over a few pages if the current apps displayed are under the list of “Downloaded” apps), once you see the list of
ALL your apps scroll down and find the
Voicemail application, tap to open it and then deselect the
Show notifications option. You may get a warning letting you know that if you do this then you may miss important alerts for this app. Press
Ok which will remove the checkmark and disable this setting; once it’s disabled press the option again to enable it.Just make sure that “Show notifications” is check marked again as you’ll want to know when you get new voicemail messages.
maybe try reading this
galaxys5guide.com/wp-content/uploads/2014/04/Samsung_galaxy_s5_user_manual_SM_G900V_Verizon_Kitkat_English_201404.pdf