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.
At present, you have to record your greeting by recording directly into the iPhone microphone -- the results of which are average, of course.

Follow the instructions and press that number. 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. From the home screen, select the Phone app. Note: Alternately, you can set up voicemail by selecting the Phone app then selecting and holding the 1 key. Select Keypad, then select the Visual Voicemail icon. Select Start. Select Ok. From any Home screen, tap the Menu key. Tap Settings. Tap Call settings. Tap Voicemail. Tap Voicemail again. View the voicemail number. Press and hold the 1 on your device’s dial pad to call and connect to your voicemail. Press the star * key to access the main menu. Press 4 to access the mailbox options. Press 7 to change the language of the voicemail prompts to either Spanish or English.
Once you’ve set up your voicemail, you’ll be able to turn off your phone whenever you want. There are, however, alternative means by which you can keep in touch. What is the procedure for resetting voicemail on a Samsung device? Modify the greetingTo access the Apps menu from any Home screen, select it from the drop-down menu.Select Visual Voicemail from the drop-down menu.Select the Greetings tab from the drop-down menu. To switch to an existing greeting, simply tap the greeting you want to use.