You need to set up a feature access code for TAAS, put it into your system abbreviated dial form.Program an ATD-qcalls key on the 6400 set and the abbreviated dial which can lable as "answer". Once you do that incoming calls will beep at the 6400 set and can be picked up using the answer key, as long as the Console is busy on an active call already. If you want it to work on the first call, yoy have to add the same keys to the Console & leave the console in Pos busy, then use the answer key to answer calls on the console as well. You have program attendnat backup into the Console Parameters form.