You will be asked to delete your current Voicemail greeting. Click on the ‘Yes’ button that appears on the screen if you want to remove that. You can save your new recorded Voicemail greeting or can use the default recorded option. Wait and hear the new Voicemail greeting message that the instructions speak out. If you want to keep that recording as your Voicemail greeting, then save it. Or you can re-record the message to get a different greeting.
If your voicemail has been set up and you are unable to change your greeting through the 'Voicemail' tab, dial *86 then choose option 4 to change. From a Home screen, tap the Phone app . If an app isn't available on your Home screen, swipe left to access the App Library. Tap Voicemail then tap Greeting …

Note: If necessary, delete an existing greeting (limit of 2 greetings) to make room for the new greeting: Tap the Menu key, tap Delete greetings, tap the check box next to the desired greeting, and then tap Delete. Tap the Record icon to record your greeting. Tap the Stop recording icon to stop recording. Start by tapping on the phone icon found at your iPhone’s home screen. Go to the setting section on your iPhone. Now, you can go to the keypad on your phone and then type the number #404 and then call so that you are able to turn off voicemail on iPhone. How do you delete your voicemail greeting on iPhone? Tap Voicemail, then tap a message. Do any of the following: Play the message: Tap . Messages are saved until you delete them or your carrier erases them. Share the message: Tap . Delete the message: Tap . Why can’t I change my greeting on my iPhone?
To save voicemails on most Android phones: 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.”