I need help regarding setting up voicemail on Samsung Galaxy S5.
To set up voicemail, open the Dialer and tap on 1 then Call. You will be prompted to input the voicemail number if you don't have one. Assign the voicemail number from your carrier network and then tap 1 again and Call. You will be greeted to set up the voicemail, password, message, etc., and that's it. This works for all countries. The S5 also features Visual Voicemail.
You can see a customization guide here: http://support.sprint.com/support/tutorial/Set_up_and_access_Visual_Voicemail_Samsung_Galaxy_Sreg_5/52036-467