A voicemail greeting is a simple message that plays before callers leave a message. It may play either when you don’t answer or if your phone is off. A professional greeting may encourage people to leave messages, which in turn makes it easier for you to get back in touch. Keeping that communication open and efficient may lead to better business relationships. It also helps you put forth a professional image for your business.
To set up voice mail, tap the Phone icon, tap the Voicemail icon and then "Greeting.". There are two options available: Default and Custom. If voice mail hasn't been set up previously on your phone, Default is selected, which means people will hear your wireless carrier's generic voice mail greeting when they call you.

Visual Voicemail works with iOS 8 and later versions. For an update, visit the Apple website. How do I listen to my messages with Visual Voicemail?
I got a new cell phone recently. As the world stood in line to pick up the latest iPhone 8, I graduated to the 6S. I pride myself on that actually. As with all new phones in the 21st century, the voicemail must be set up anew. I used the default message for the first few days, but finally settled down to record a more personal greeting.