I've assembled this list in mid-nineties from the messages that people were emailing around. As far as I know, the author of this list is unknown.
And remember, while you’re busy returning your calls, Blitz can be automating other parts of your sales process. We can assign leads to your staff or even send emails to your customers.

The greeting that you leave on your phone in the form of a voice mail can be very important as it is the first contact that anyone calling has with you or the company that you work for. Therefore it is important that your voicemail greeting is drafted in such a manner that it does not make the caller squirm in embarrassment, or even raise their eyebrows in sheer wonder. Proper voicemail etiquette demands that a good voicemail message convey information like whom the caller is calling, where they are, when the caller can expect to be called back, and what to do if the call that is being made is of an urgent nature.
Nobody wants to listen to a long-winded voicemail. Keep your greeting short, simple, and concise. A voicemail message should pique a client’s interest and leave them looking forward to your call. Stick to the basics, explaining your company name, hours of operation, and when to expect a callback.