Personalized Voicemail message

[Whiskeypawz]

I know there is app available that will let you personalize your voicemail message to each caller. For example, your doctor's office could hear the standard "I'm not available, please leave a message." & your mom could hear "I'm in church right now so I can't answer your call." Silly, but you know what I'm getting at.
I know Google Voice is not the app but I'm also pretty sure Google Voice has lots of cool new features. Is this one of them?
Does anyone know what the name of the app is that I'm referring to?
I saw it in a forum on here months ago but didn't find it when I did a search.