AASTRA DT4x2 for MX-ONE User Guide EN - Manual (Page 74)

Absence Information
DT412/DT422/DT432 74
Cancel for another extension #230*
Dial.
е # ж
Dial the extension number and press.
Wait for the call icon to stop flashing.
Note: If the special dial tone is received, the Authorization
Code for the other extension is required. Add the code and
press
#
before pressing the Hook key. æ
Press to finish the procedure.