Ericsson DT59C - Manual (Page 20)

Description
DT590 20
User busy menu*
Callback or Call Waiting on internal calls can be initiated if the called
person is busy.
Call Waiting menu
Not applicable for the MD110 system.
Note: *)This menu function requires that the
corresponding code has been downloaded to your phone
using the PC program Cordless Phone Manager. Please
contact your system administrator.
Additional display features
Depending on which network you are connected to, additional
display features are available. Ask your system administrator if you
require additional display features.