Learn how to customize the voicemail settings on your Samsung Galaxy S4. For that you had to customize the voicemail service provided by the carrier you are using.
Voicemail service on Samsung Galaxy S4
From the Home screen, tap Apps > Settings > My device tab > Call > Voicemail Service.
Voicemail service provided by your carrier is the default.
Tap My carrier to remove the carrier Voicemail service.
Voicemail settings on Samsung Galaxy S4
You can view or modify your voicemail number from this menu.
From the Home screen, tap Apps > Settings > My device tab > Call > Voicemail settings.
Tap the Voice mail number field, backspace to erase the digits, and enter a new voicemail number using the keypad, then tap OK.