Need some help with making a single line extension give busy tone when on a call instead of ring back to the caller. I have looked in what I thought were the obvious places in programming and I am sure I will feel silly once i know the answer. Basically we want to caller to get a busy signal if that extension is on another call. Currently the caller hears ring back if SLI extension is busy.Thank you in advance for your help.

Go to A screen and set "busy on did" to Y
This busy will only be applied when the phone has received a call on its direct inward dial number.