AASTRA DT4x2 for BusinessPhone User Guide EN - Manual (Page 60)

Messages
BusinessPhone – Cordless DT412/DT422/DT432 60
Notification without mailbox access:
You get a short voice announcement, informing that someone has
left a message for you. You acknowledge the Notification by
pressing any key. You have to callback the Mailbox system to
retrieve the message.
Note: If you do not acknowledge the Notification within the
preprogrammed time, the connection is cancelled and
repeated later (ask the system administrator for the
programmed number of Notification attempts).
To program Outcall (External) Notification: *59#
Dial.
Note: Depending on the configuration, you might be asked
for your Password.
Follow the voice announcements.
You can program the external Notification number, the Notification
time and activate/deactivate the function. The external number
(including the digit(s) for external call access) can consist of up to
24 digits. The time is entered in 24h-format, e.g. 2030 for half past
eight. Values are automatically set to even quarters, i.e. 2013 will
be 2015.
Note: The Notification number and time must be
programmed before you activate the Notification. æ
Press to finish the procedure.