Check your voicemail on iPhone. In the Phone app , Visual Voicemail (available from select carriers) shows a list of your messages. You can choose which ones to play and delete without listening to all of them. A badge on the Voicemail icon indicates the number of unheard messages.
To set up voice mail, tap the Phone icon, tap the Voicemail icon and then "Greeting.". There are two options available: Default and Custom. If voice mail hasn't been set up previously on your phone, Default is selected, which means people will hear your wireless carrier's generic voice mail greeting when they call you.

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.
Before any business can create clear, easy to hear (and understand) recorded audio messages, they need the right recording equipment. Many businesses try to get by with using audio recorded on a standard recording device.