Website: https://www.onsip.com/voip-resources/smb-tips/after-hours-voicemail-and-auto-attendant-greetings
Avoid telling your prospect what to do. You'll make returning your call seem like a chore or, worse, a demand. This should feel like a mutually beneficial relationship -- one in which each party wants to call the other back -- unprompted.

With Visual Voicemail, you can see a list of your messages and choose which ones to listen to or delete. Learn how to set up and transfer your existing voicemail. Create a voicemail password, then tap Done. Enter your password again to confirm it, then tap Done. Select Custom or Default. If you choose Custom, you can record a new greeting. Go to the Phone app, then tap the Voicemail tab. Tap Set Up Now. Enter your password,* then tap done. Record a custom greeting or use the default greeting, then tap Save.
Here’s a simple clinician voicemail script if you want to keep your message to the point. Hello. You’ve reached Highland Family Counseling Services. We are currently unable to take your call, so please state your name, phone number, and a detailed message after the beep. We will return all calls within two business days.