The message waiting lamp at the top-right corner of the phone can also be used to indicate when you have a call alerting your phone. The lamp is flashed to indicate a call waiting to be answered.
1.Press the 
button.
2.Use the up and down cursor keys to highlight Options & Settings. Press Select.
3.Use the up and down cursor keys to highlight Call Settings. Press Select.
4.Use the up and down cursor keys to highlight Visual Alerting. Press Select.
5.To change the setting, press Change.
6.When completed, press the Save soft key.
7.Press the Back / Exit soft keys to exit the menus.