To Remove "Dial 9" Feature:
Press Program
Enter 19
Press Enter
Press "SEL" key till it says "Idle Line"
Press Enter
Lift and Lower Handset to exit programming mode
To Add "Dial 9" Feature:
Press Program
Enter 19
Press Enter
Press "SEL" key till it says "Intercom"
Press Enter
Lift and Lower Handset to exit programming mode