One of the first things you might want to do when you set up a new Samsung Galaxy S10 is to record a voicemail greeting. Unfortunately, it's not obvious how to do that, so many people make do with the default greeting.
Update, the database doesn't appear to store the length of the audio file, so it shouldn't be a problem if the original and replacement audio are different lengths. Inserting an entry into the "v_voicemail_greetings" table should resolve the GUI "seeing" the greeting, but there is a voicemail_greeting_uuid column that is a long string of hex. I can randomly generate something, but does anyone know if it needs to be stored/registered/etc elsewhere? Sep 29, 2016 2,686 465 83 Aug 16, 2018 #5

-Hi, this is ______. I’m sorry I can’t answer the phone right now. Leave a message, and then wait by your phone until I call you back.
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.