While they are listening to your voice, they are internally deciding whether or not it is worth their time to continue or hang up. Look at your voicemail message as its own short advertisement.
Many of our customers also choose to use services like Fiverr to get quick, quality audio for their voicemail greeting. How many voice mail extensions do I get?

8.) Benvenuti al Servizio Assistenza della John Doe. Purtroppo, tutte le linee sono occupate al momento. Si prega di lasciare un messaggio dopo il segnale con il vostro nome e numero di telefono. Vi richiameremo al più presto possibile. Vi auguriamo una buona giornata.
Users often don’t invest enough time into their messages, resulting in incomplete, unprofessional, or otherwise under-whelming greetings. Sure, crafting a greeting doesn’t sound all that complicated; however, there are a number of pitfalls users can fall into—i.e. informality, terseness, sincerity, lack of direction, and more. While none of these sound too catastrophic, they are often interrelated. As such, they tend to worsen any problem. For example, humor can cause informality, worsen ambiguity, and weaken sincerity. That being said, users should strive to avoid ALL these pitfalls.