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.
You don’t have to spell out every single thing that you think they might want to know. Have some faith that your callers will be able to figure things out on their own. Be natural but informative.

It is a voice message for the caller when you aren’t there to receive the call. Caller can leave a voicemail message for the person for which he/she has made this call.
It would help if you conveyed as brief as possible any information or menu options you would like to give callers. Your message might include instructions for callers on how to bypass it in the future. 7 Best Business Voicemail Greetings that prospects and customers are also busy. There may be one greeting you want to use during business hours. Another greeting for after-hours. Each greeting might convey information specific to the period. Sometimes callers wish to details about your business hours, whereabouts, or other pertinent information.