Voiceover classes

Hey, so I don't really know the official title of this, but has anyone taken voice classes?

Not like singing or acting, but just talking, like how you sometimes hear your voicemail say please enter your password, then press pound. I have always been interested in taking those types of trainings to get better at it, although I'm already really good at it because I'm surrounded by voiceovers all the time so I know how to speak in that type of voice, but I just wonder how I can take it further.

If anyone has any input that would be grately appreciated, thank you.