They used the same gate system at my last apartment. It was pretty useless. I had two other roommates and guests would come over all the time, so my phone was always going off. I had a special ringtone when I got a call from the gate and when I heard it, I would just hit 9 reflexively without even thinking about it. I was surely not the only one in the complex to do this -- so if you wanted to get in all you had to do was dial one apartment after the other until somebody let you in without questioning you.