AASTRA 4425 IP Vision (SIP) for MX-ONE User Guide - Manual (Page 73)

Absence Information
Dialog 4425 IP Vision 74
Cancel for another extension #230* z #
Dial, enter the extension number and press.
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 Call key.
Call Press.