Rather than waiting for a callback, open up additional channels of communication with your callers by inviting them to email. The most professional voicemail greetings often include an alternative method of communication.
3.) Benvenuti alla John Doe. Al momento non possiamo rispondere personalmente alla vostra chiamata, oppure ci state chiamando fuori dall’orario di lavoro. Si prega di lasciare un messaggio con il vostro nome e numero di telefono – vi richiameremo al più presto possibile. Grazie e arrivederci.

Typically, most of these services are uniform—i.e. include the same tools and features (send a script, they record it in a tone you approve, they send it as a file, you supply any feedback, etc.); however, there are some services that go above and beyond. For example, VoiceOverPro, is a single voice professional who records 30 second voicemail messages based on users’ scripts. This is standard; however, users also have options like adding music, recording up to 60 seconds (or 150 words), rush, 2-day turnaround, and even same day delivery.
If you are the sole employee of your business and your business communication generally makes that clear, it is fine to refer to yourself in the first person.