I have a site that has a Partner R7.0 and one user is having to manually press the ringing line button to answer it. He said when a call comes in his phone will ring and then immediately beeps once and then the green light flashes next to the line the call is coming in on. When he picks up the handset he ends up picking up the first idle line and then he has to manually press the line button that the call is ringing in on. He doesn't have a DND button on his phone but could that be activated?