Overview
Mitel IP phones offer the ability to leave a callback message instead of a recording a voicemail message asking someone to get back to you. This can be done in two different ways which function differently.
After dialing a number, there will be a button on the display that says Call Me Back. Pressing this will leave a voicemail message in that user's mailbox and will light up the voicemail light. This will prevent the user from accessing their voicemail until it is cleared. To clear this message, the user will have to press the voicemail button while the phone is on the base which will display a message. The user can then press Read Msg and then Erase Msg, which will then allow the user to access their voicemail again.
The other method to use this feature is to dial a number and then press the voicemail button. The next time that the person you dialed hangs up their phone, your phone will ring prompting you to call them as they are now available. Picking up your phone at this point will dial the user you originally wanted to call back. This behaviour will continue until both users pick up the phone and connect on a call, as the call will be considered "completed" then.