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.
Here are some helpful links to help you record voicemail greeting that is clear and professional. Record your phrases for recording a great voicemail greeting here. Record yourself and compare it with a native speaker. Hear Georgie giving helpful feedback to other students on their voicemail greetings.

Your clients don’t have a lot of time, and neither do you. Use the following short voicemail greetings to get to the point quickly and invite them to leave a message.
The most important aspect of a voicemail message is that the listener must be able to understand your message. Don’t mumble your words and be sure to speak loudly and clearly. Speaking softly will make it difficult to understand you and may result in the listener not being able to call you back.