After creating, the Voicemail Greeting, you can test it by calling to your number from another phone, and see if it is playing correctly or not. Open the Phone App. On the lower screen, tap on the Voicemail option. Select Custom, with this option, you can record the personal voicemail greeting on the iPhone. Tap Record, to start recording the voicemail greeting message on the iPhone. Greeting samples are given in this article below, Once you are done with recording, tap Play to listen. Lastly, if everything is alright, and custom voicemail recording is perfect, then tap Save.
Conducting extra research on your prospects before you call them is always a good idea. This script from Mike Brooks is a great example of how you can use this additional information in your sales voicemails.

Don’t Get Creative With Your Voicemail Messages—Many high profile sales trainers advise you to leave all kinds of crazy messages on your voicemail as a way to stand out. What I find is that most of the people who try to do something creative with their voicemail messages end up sounding corny. In fact, seldom do creative off the wall voicemail messages make a positive impression on me. If you want to be viewed as a professional, then make sure your greeting presents you as one.
A professional voicemail greeting is a recorded message that welcomes callers to your business when no one is available to pick up the call. For a polished call experience, the greeting should reflect who the client is calling – whether a general business number, department, team, or individual – and when the customer can expect the call to be returned.