If you are fowarding from one line to another and getting the call waiting tone. Then you need to set the service parameter for "toneoncallfoward" to false. This is system wide. If you are not forwarding from one line to another and just want to disable call waiting this can be done systems wide or on a per line basis.
System wide is the service parameter and per line is on the line configuration page.
Thank you,
-Mckee
