An extension is a short internal number. Extensions allow users to make and receive calls. You can assign extensions to every employee in your organization.
Send a message. Call into your voicemail. Press 2 to send a message. Enter the mailbox or distribution list number you want the message to go to. Record your message. If you want to schedule the message you just recorded to go out later: Press 4 for delivery options. Press 4 for future delivery. To deliver it today press #. To deliver it on a

To change your Standard Voicemail greeting follow the directions below. Enter your password and the press # key. From Shoretel Communicator (You will need to have access to your Shoretel phone to record the message) In the menu bar, click More, then Prefereces. Your phone will turn on and beep. Begin your message.
If it is the first time you are using the Voicemail, you should set up or change your default voicemail on iPhone 7 first. If you have set up the voicemail, you can skip to next part. Or else, you can get some helpful information to set up voicemail. As different carriers may have different ways to set up voicemail on iPhone, the part just take AT&T for an example.