Why won't my number pad work?

[AC Question]

I have a Samsung Galaxy s5 and everytime I try to call voicemail and put in the password, it won't let me in. I realized that I can't put in a code for any number I call for example if I want to be in a conference call, my phone won't allow me to put a password in. Can you help please? Thank you

 

[B. Diddy]

Welcome to Android Central! Open the Phone app, tap Menu>Settings>Call Settings, and look for an option for DTMF Tones. Make sure they're turned on, and set them to Long.