You can block or unblock a number on an Android phone using the built-in Phone app's "Blocked numbers" menu.
To call your voicemail on an Android phone, open your phone's dial pad and hold your finger down on the "1" key.
I've spent large portions of my life looking for ways to extend the battery life on my Android phones. Admittedly, that sounds rather dramatic, but growing up with only budget models meant I was ...