The longer it gets, the more likely your potential client will hang up because they are annoyed.
Friends and colleagues speak to each using first names only. So do people of authority. They do not call each other and leave voicemail messages asking for Mister, Miss, or Mrs. Therefore, when you call a person you want to do business with and you leave a voicemail message, refer to them by their first name only. Don't say mister, miss, or misses. Don't say their last name. Begin your voicemail message by saying only "hi/hello" followed by the person's first name. Or, you can even forget the "hi/hello" and just say the person's first name. That is how you show confidence and authority and separate yourself from weak salespeople.

Hello, this is David. I don't live here, so if you were trying to call me, you've dialed the wrong number. On the other hand, if you were trying to call John, Jim, or Eric, please leave your name and number at the tone. I don't guarantee that one of them will call you back—only that I won't.
We know that the only way to live a blessed and happy life is to live out the Golden Rule. And we know that manners (from the Latin word for hand…how to handle something) give us mutually agreed upon best practices for putting the Golden Rule into practice in our everyday encounters. They also help us know what to expect from one another and set gracious boundaries.