AASTRA DT4x2 for MX-ONE User Guide EN - Manual (Page 90)

Other Useful Features
DT412/DT422/DT432 90
DISA = Direct Inward System Access
If you are assigned to use this function and you are working
externally, you can call your office and get access to an external line
in order to make business calls. The business call will be charged
your office extension number or an account number. You will just
be charged for the call to the office.
The external phone must be of push button type provided with
pound key (
#
) and star key (
*
) or a mobile phone adapted for dial
tone pulses (DTMF).
After a completed DISA call you must hang up before a new DISA
call can be made.
There are different procedures depending on the type of
Authorization Code, or when an Account Code is used.
With common Authorization Code z
Call the DISA function at your office.
Dial tone. *72*
Dial.
z #
Dial the Authorization Code and press.
Dial tone. z
Dial the external number.
With individual Authorization Code z
Call the DISA function at your office.
Dial tone. *75*
Dial.
z *
Dial the Authorization Code and press.
z #
Dial your own extension number and press.
Dial tone. z
Dial the external number.