You can reach me by calling (your number). That number again is (your number), and ask for _________. I look forward speaking with you and thanks in advance for returning my call.”
It is no surprise that your actual voice mail greeting must be delivered in the same way: Professional, clear, brief, and to the point. In a previous blog, "Marketing Messages on Your Cell Say You Mean Business," some techniques for making a professional voice mail greeting were discussed. There are many similarities between leaving a voice mail, and producing a voice mail greeting. You want your callers and receivers to hear a confident and professional person on the other end delivering a coherent message. You should introduce yourself to a prospective client in a personal way. An email doesn't generate much discussion, nor does it necessarily show you went the extra mile in contacting the client. Generating conversation. A professional, well conveyed voice message shows the voice mail receiver that you are confident and well-spoken, and that there is a person behind the message. Emails can be prepared, edited, and revised unlike voice mail messages An email or email chain thread is documentation of a conversation that can easily be referenced In an email you can include a phone number, address, website, etc that may be hard to remember or record through voice mail communication Emails can be forwarded, CC'ed, and blasted.

The first two are voicemails for prospects you haven’t spoken with yet, the next one is for when you’re calling a prospect or client back, and the last example is for when your prospect or client isn’t calling you back at all:
Additionally, you will want to close out your voicemail by (re)stating your contact information and name and purpose of your call. This is another little trick of leaving voicemails - people tend to remember the first and last things you say more so than the middle, so by summarizing the important pieces of your message at the end, what you said is more likely to stick.