AASTRA DT4x2 for MX-ONE User Guide EN - Manual (Page 75)

75 DT412/DT422/DT432
Messages
Messages
When you receive a new message, the flashing lamp, accompanied
by a message tone and/or a vibrating phone, give you notice of a
message (a special dial tone can also be used to indicate a waiting
message, if programmed).
The New message icon is also used to indicate a new message. In
addition you can see the number of queued messages in the
display.
The message tone can be silenced by a press on the Mute key.
Notes:
The message tone will break through silent mode if the
message is urgent.
The message list is cleared when your phone is switched off
or the power of your phone is lost.