Mitel 600 User Manual page 31

Other Options menus for normal and urgent jobs are
described in "Confirmation of a Job" on page 13.
Tip: To delete all messages in the Inbox list or in the
Jobs list including unread messages, you can use the
Security > Reset to default > Inbox/Text messages
menu entry. The Security menu can be accessed via
the PIN (Personal Identification Number). The default is
"0000".
Using the Options Menu
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