If you want them to leave a voicemail, tell them right from the beginning, “Please leave your name, reason your calling, and the best way to contact you.” If you want them to call you back during normal business hours, tell them, “Please call back during normal business hours.” If you want them to call back prepared for a lengthy conversation, you can say something like, “Please refer to our website’s FAQ page,” and then provide the URL. Self-service should never be underestimated.
27. Hey, this is [your name], but you should know that already since you called me. I’m obviously not here right now, so I won’t patronize you by telling you what to do after the tone.

To improve a a business voicemail greeting, keep these eight rules at the forefront of the creative process: Avoid turning customers off with overused and impersonal phrases like “your call is very important to us..." Avoid leaving customers unsure by not immediately telling them the business, department, and/or person they’ve reached.
If it works better for you, offer your callers the option to email you, or even send over a text to a VoIP texting app, or even your personal number if you don’t mind. Many people will prefer the ability to quickly text or email, and callers will appreciate the increased level of service.