Keep it Brief. Time is money in business, so if your voicemail is long, chances are the caller will simply disengage before the cue to leave a message even sounds. Keep your voicemail short. The most should be around 30 seconds, and even that’s pressing it. We’ve grown into a country where our attention span can last only about 10 seconds in some cases, so keep it short, brief and to the point. Persuade and Engage the Caller. If someone calls your business, they already have an intention. It’s the quality of your voicemail that plays a factor if they consider you a company they’d like to deal with. This is your chance to motivate someone to engage in a meaningful conversation with you. If your voicemail is shoddy, chances are they’ll hang up, or lose motivation to continue the call. In other words, your voice mail must engage and entice someone to the point that they care enough to leave you a message.
First you need to know how much time your phone system or provider allows for the duration of the greeting. Some are 30 sec some are longer. Then you need to have a few ideas of what you want to say, or ask your callers.

What does your greeting have? Is it the automated one or have you personalized it to suit your personality? Many times, when we call our friends, family members, or any other places, all we get is the voicemail. But when that message on the other side of the line is plain, it can really put someone off. You voice message greetings are supposed to be fun, energetic, and witty so that the callers want to pick up their phones and give you a call just so they can listen to the greeting again.
Hi! John’s answering machine is broken. This is his refrigerator. Please speak very slowly, and I’ll stick your message to myself with one of these magnets.