2. Voxist. Voxist is one of the great visual voicemail that allows users to manage voicemails conveniently and smoothly, anywhere they go, and also let them read transcribed voicemail messages.
First you need to know how much time your phone system or provider allows for the duration of the greeting. Some are 30 sec some are longer. Then you need to have a few ideas of what you want to say, or ask your callers.

A good voicemail greeting is short and professional, lets people know that you’ll get back to them, and invites callers to continue engaging with a call-to-action. You should also show your personality if you’re in an industry or role that allows that. If your industry is more conservative, however, you’ll want to keep humor and personal touches to a minimum. A greeting Your name Your company A simple explanation for missing the call (e.g. you’re away from the phone or are on holiday) A rough estimate of when you’ll get back to the person An alternative person to reach out to (if you’re out of office) An alternative mode of communication (if you prefer email or text) A call-to-action such as “Leave a message” or “Send me an email at [email protected]”
If someone is listening to your voicemail greeting it's only because they intend to leave you a message. Don't make them listen to 3 minutes of rambling in order to do so. Plus, you're more likely to deliver a clean, professional read if you stick to shorter greetings. If more specific information is needed, direct callers to where they can find it on your website.