Setting up voicemail on an iPhone is pretty easy. These steps are specifically for iOS 14 and above, but they should be nearly identical for people who are still using older operating systems like iOS 12 or iOS 13.
If you’ve already created a custom voicemail on your iPhone, you can tap Play to see how your voicemail sounds. If you’re interested in creating a new message, tap the Custom button. From here, you can start recording your message by tapping Record and tapping Stop whenever you’re finished. Once you’re finished recording, tap on Play to make sure the message comes across as you’d like and hit Save (in the upper right) to save it as your voicemail.

3. Then jump down to the "Voicemail Forwarding" section and enter the email address you would like your voicemails to forward to. 4. Next, got to "Voicemail Greeting". To record a greeting select “Add your own greeting”. Then select “record by computer” this will launch the recording tool. Once you are happy with your recording, save it ...
Open your Voicemail app.Tap, or tap and hold the message you want to save.In the menu that appears, tap the one that says “save”, “export” or “archive.”Select the storage location in your phone you would like the message to go to, and tap “OK” or “Save.”