Step 8: All call recording audio files can be found in the My Files app in Internal Storage > Call folder. You can also view all call recordings from the Phone app by going to Phone app > 3-dot menu button > Recorded Calls.
The telephone systems have the feature named as Voicemail. VoIP is the best example of it. When a receiver is unable to pick up the phone, then the caller can leave the voice message on the receiver’s phone. In older telephonic machines, such messages were stored as a voice message directly, and the receiver can hear them later. In modern telephone systems, such info is being stored on the server of the service provider in the user’s mailbox. It is similar to email in which the messages are saved in the form of audio instead of text.

Visual Voicemail is an iPhone feature that provides visual access to voicemail content. It enables you to select the message you want to listen to, without going through all of your voicemail messages.
Open the Phone app (the green icon at the bottom of your home screen), then go to the Voicemail tab. Go to Set Up Now. Create your voicemail password and tap Done when complete. Enter your password again and tap Done to confirm. To select a greeting, choose Default or create your own by selecting Custom, then tap Done when complete.