These issues limit the quality of the recording because the amateur actor doesn’t know how to speak with the proper enunciation and cadence for phone system recordings, and there’s no experienced director handy to provide guidance.
What you do not want to do is say your phone number so quickly that the person has to listen to your voicemail multiple times to try and figure out your phone number. We have all gotten those annoying voicemail messages where the person said their phone number so quickly that we had to listen to their message several times to figure out their phone number. Don't be that jerk who leaves their phone number so fast that the other person has to listen to your message over and over to try and figure out what your phone number is.

1. Personal Business Voicemail Greeting. Your personal voicemail greeting should be brief and to the point. State your name and your availability, project a welcoming aura, and ask the caller for whatever information you need from them. Hi, you've reached the voicemail of Mike Downing. I'm not available to answer the phone right now.
An excellent business voicemail greeting conveys your level of professionalism and competence while also providing your callers with a glimpse into your company’s culture and level of care. As minor as it may seem, your voicemail greeting can instill confidence and trust in your callers or it can be a cause for concern.