I am using CUCM 7.0, my client require that he need call waiting if he is busy on the line and the third person is calling it should show him call waiting and. i try to change busy trigger, but it gives busy tone which he dont want. he want call waiting so that the customer will come to know he will take my phone .. please help how can i cange the opention in cucm to make this task active. is if possible in this version.