If you get a voice mail like:
"Hey, it's John, call me back."
are you ethically required to actually call the person back?
Normally I would but I just picked up one of these messages and I thought, hey, I'm really busy and you didn't give me any reason to go out of my way to go call you. The best part is the voicemail was left at the office at 6:30pm when the guy knows I leave at 5pm... smells like someone just wants to throw the ball in my court about a topic I have no awareness of. So who has the responsibility to follow up? Me or the caller?