AASTRA 4420 IP Basic (SIP) for MX-ONE User Guide - Manual (Page 48)

Other Useful Features
Dialog 4420 IP Basic 48
Other Useful Features
Account Code (optional)
This feature is used to charge a call to an account number or to
prevent unauthorized calls from your phone. The Account Code
can have 1 to 15 digits. u
Lift the handset. *61* z #
Dial, enter the Account Code and press.
Press
Dial tone.
Note: Finland and Norway, dial
* 7 1 *
Code
#
.
z
Dial the digit or digits to get an external line and the external
number.