This tutorial is going to show you how to record a voicemail greeting that you choose. It is a good idea to either write out or think about exactly what you are going to say before you record the message. You will then have the opportunity to play the greeting back before you set it for any incoming calls that go to voicemail.
Open the file you want to store.Tap Select, the file name and then Organize, which looks like a little folder.Under “On My [Device name],” choose a folder or tap the icon of a folder with a plus sign to create a new one.Tap Copy and you’re done.

3. Force close and reopen the Phone app. To force close Phone, on iPhone X and later swipe up until you see the apps in task view, then swipe up again on Phone.
3. Enter your Pin Number. You will need to know your pin or passcode in order to check your voicemail. If you don't have this code, you will have to retrieve it from your carrier. You will hear instructions to input your pin. Hit the pound key after you enter your pin. Follow instructions on how to listen to your voicemail. It's usually to push a certain number (like 1). That's all there is to it. You should be able to hear your voicemail messages now.