voicemail and call waiting not working at all

[xstien]

I recently had to get a replacement 4s and I missed a call and called back and was told they left a voicemail then I started thinking, wait when was the last time I ever got a voicemail? A friend said he has twice. So I went to check things out and go to voicemail and there is nothing there except the greeting icon. I changed my password twice, no change. I reset network settings, no change. Then I realized the old phone had the same exact problem with voicemail. SO I go to call it, and I'm told I have NO voicemail's when I know I should have at least 3. So that's one issue. The other is call waiting has never worked for me. It's only happened a few times but every time I go to reject incoming or swap calls either way phone completely hangs up on both parties. I have no idea if this is an iphone thing or a verizon thing as I've searched the net and read q&a's and forums and no one else seems to have the exact issues I do, or maybe they just don't use forums. Any help is appreciated.