Most of the time this error is caused by the connectivity of your phone to a cellular network or WiFi connection. The easiest way for solving this issue is by turning the Airplane Mode ON. On your main screen of the phone, you can swap down the notification bar and tap on the Airplane Mode option. Once it is ON all the connectivity to your phone will be turned off. You can wait for 30 seconds and then turn it back OFF by using the same method. This option can vary depending on the device you are using. For some devices, you need to go to settings or use the power button on the phone to get to Airplane Mode. After applying this method, you can now try updating or setting up the voicemail greeting on your phone.
6 hours agoVisual voicemail is a feature that allows you to do the following: Receive and listen to messages in any order. Scroll through messages visually. Save, archive or delete messages by touch. Get transcription of messages (for most) Send voice messages via email or text. If you own an iPhone, you've likely been using visual voicemail already.

For those with voicemail greetings that get changed about as often as a new president is elected, know that this is doing a serious disservice to the caller-recipient relationship. It signals to callers that the business is anything but an authority, most likely not very detail oriented, and has questionable overall credibility and competency. Those aren’t traits that any business wants to associate itself.
When you reset network settings, all of your iPhone’s Wi-Fi and cellular network settings will be erased. This includes your Virtual Private Network (VPN) settings, your Bluetooth devices, and your Wi-Fi networks — so make sure you write down your passwords first! We do this step because it can be very difficult to track down the exact source of a software problem, so we reset all network settings.