Tap Voicemail in the bottom right corner. 3. Tap Greeting in the top left corner of your screen. In the top left corner, tap Greeting to edit or change your outgoing voice message. 4. Tap Custom if you want to record a custom greeting. To record a personalized message, tap Custom. This will give you options to record a new one.
We’ve heard frightening stories of people who have been hit by huge bills because of annoying marketing calls that went to voicemail, so that's something you really need to avoid, such as this article in the Telegraph.

To commemorate the tenth anniversary of the iPhone, Apple marketing chief Phil Schiller sat down with tech journalist Steven Levy for a wide-ranging interview about the smartphone's past, present, and future. The report first reflects upon the iPhone's lack of support for third-party apps in its first year. The argument inside Apple was split between whether the iPhone should be a closed...
Thanks for calling Dial-A-Shrink. I can’t come to the phone right now, so after the tone, please leave your name and number, then talk briefly about your childhood and tell me what comes to mind when you hear the following words: orange… mother… unicorn… penis. I’ll get back to you with my diagnosis as soon as possible.