Here, the ophthalmologist is not in a position to receive a call. However, he/she makes sure the patient’s need is addressed.
Humor also leaves a lot of room for misinterpretation—which subsequently weakens sincerity and authority. A caller can be very turned off by merely misinterpreting your joke. Why take this risk? Additionally, this could even cause callers to question your character. Say, for example, the president of a company’s mobile phone voicemail greeting was funny. What’s to happen if the caller didn’t like or get the joke? What if they found it offensive? Another scenario is that a caller is reaching out to you for the first time—i.e. they have no idea regarding your personality. What next? The point is, with this type of greeting, humor is bound to be more divisive so just avoid it altogether. c. Poorly Pacing Your Message and Bad Time Management: Don’t speed through your message. Speak clearly so callers know what to include in their message and when to leave the message. At the same time, don’t drag your message out. No one wants to sit through a diatribe. Just get to the point clearly.

Expanding on the simple approach above, let the caller know who they've reached. This will not only eliminate people leaving voicemails by mistake, but it will reassure the caller that they have called the number they intended.
We actually know a top insurance sales guy who did a sales motivational message every day just like this, and people used to call just to listen to his thoughts.