Find "Call Waiting"
Press Connect.
Press the Menu key.
Scroll to Options and press the Navigation key.
Scroll to Call Waiting and press the Navigation key.
Activate or deactivate
Highlight the drop down list next to Call Waiting Enabled and press the Navigation key.
Highlight No or Yes and press the Navigation key.
Save and exit
Press the Menu key.
Scroll to Save and press the Navigation key.
Press Disconnect to return to standby mode.