Responding to voicemails is time-consuming. Fortunately, with the right greeting, you might be able to save yourself some hassle. If you don’t have an auto attendant, you can give callers the information they are looking for with your voicemail greeting. Of course, this means that your greeting may be a little lengthy, but that can work in your favor as callers will only stay on the line to leave a message if they still need assistance.
As Dan tells us, "This is the only strategy I’ve ever seen consistently work—but when they call back you'd better have a question ready!"

It’s the way that people contact you when you are busy with other clients or customers, and cannot get to the phone. It is often the customers or clients first impression of your business or brand, you need to leave a great impression. The worst thing is for a first time caller, or even a returning customer, to get a short blurb like “Leave a message i’ll call you back”. Or, just a beep after the ring.
In Australian English it’s pronounced with the vowel /a:/ like in ‘part’. Problems arise when people use the /ʌ/ vowel (like in ‘up’) instead of /æ/ or /a:/. If you do this is will sound like the worst swear word in English. Many non-native speakers often pronounce the vowel /æ/ more like /ʌ/ because they don’t have a vowel like /æ/ in their first language. Many speakers of European languages will do this (Spanish speakers and Italian speakers) and also speakers of Japanese and Korean. This problem with /æ/ also means that if you say the word ‘back’ in your voicemail greeting sample, you are likely to pronounce it more like ‘buck’. remember to pronounce word endings in English. Check you aren’t dropping any endings off or mispronouncing them.