If you want them to leave a voicemail, tell them right from the beginning, “Please leave your name, reason your calling, and the best way to contact you.” If you want them to call you back during normal business hours, tell them, “Please call back during normal business hours.” If you want them to call back prepared for a lengthy conversation, you can say something like, “Please refer to our website’s FAQ page,” and then provide the URL. Self-service should never be underestimated.
Of course, if you don't answer your cell phone it goes to voice mail and plays your pre-recorded message. But what we need are phones which can answer and play a pre-recorded message for a short time. In particular a message of the form, "Hold on, I'm in a meeting and must keep silent. However, I'm walking out of the meeting right now while you hear this recording, and in a

Select “1” for default voicemail greeting or “2” for a temporary or vacation voicemail greeting. If a file is selected here it will supersede the Media file (number 1 above). Once this is set back to None the Media file will play.
*Note: Some of your users don’t celebrate all the same holidays you do. Remember to keep these voicemail greetings neutral 🌟