I can't tell you how surprised I am there is no option to define a DND button when your phone status is "connected". I also can't tell you how many teleconference meetings I've spent huddled around an IP Phone with a team on speaker and each time a call comes in, I disrupt and annoy the participants as they are forced to hear the ringing of my incoming call. Sure, you can hit DND as each call comes in, if you're sitting with your finger on the softkey and not standing in front of a whiteboard presenting. I've tried to make a concerted effort to place my phone on DND BEFORE I begin a teleconference meeting session, but often times a "Do you have 5 minutes quick?" turns into an hour long call and I wish I had hit DND before I answered.
Does anyone else find it annoying you can't place your phone in DND mode when you have a connected call? I think it's a "feature" that is sorely lacking.