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.
Your voicemail message should ideally answer all of the following requirements: Brief -- nothing bores callers as much (or makes them hang up as often) as long voicemail messages Informative -- if it's your professional voicemail, say your name, business, and if necessary, department.

The voicemail message can be anywhere between 10- 25 seconds. Keep it as short as you can because the prospects need to hear the vital details in it.
3.) Bienvenue chez John Doe. Actuellement, nous ne pouvons pas répondre à votre appel ou vous nous appelez en dehors des heures de bureau. Laissez-nous un message avec votre nom et numéro de téléphone – nous vous appellerons aussi vite que possible. Merci et au revoir.