Context does matter here. If the caller would reasonably expect you to answer the phone (such as if they were calling a store or other place of business), an apology for not being able to get to the phone makes the most sense.
2.) Siete connessi alla mailbox del Signor John Doe. Si prega di lasciare un messaggio e il Signor Doe vi richiamerà al più presto possibile. Grazie per la vostra chiamata.

We look forward to serving you so please leave your contact info, details and reason for calling after the beep. We will call you right back!
The importance of voicemail in the customer care sector has not diminished despite the arrival of newer web technologies. VoIP applications let the businesses use voicemail service with flexibility, as it is. The users need not rely on extension terminals when they use VoIP services. A strong internet connection is a prerequisite and the pre-configured phones can be used – both for calling /receiving calls and for automated custom greetings. IVR feature redirect callers to the right virtual extension where their needs can be addressed. This can be done anywhere through a web portal access and an internet connection.