RingCentral NOC Shift Manager interview questions

Somebody from recruitment called me and asked that I dropped by for an interview with their Sr. Director for NOC. I arrived at their office about 15 minutes before the schedule. I waited for about 20 minutes. No advise why. Then a lady from HR asked me to come in, their office was a maze. Lots of doors to go thru to reach the NOC. When i was in the room, i had to wait another 5 minutes standing at the door, while the Sr. Dir still talks with another guy in the room. Then I was asked to come in, sat down. No greetings or hellos from the director , no introductions of who he is or the other guy in the room. Sr. Dir just went ahead and asked questions. Then in the middle of the interview he asked me about NOC staffing from previous company so I gave him a number and explained our ops. And then he went on to contradict me, like " No you're wrong, you cant staff a 24x7 NOC with only that number of staff, blah blah blah and he went on about a computation. By the tone of his voice this is what he was telling me " You're wrong, i am right." So I just left it at that. Then he asked me about salary. Then said we will call you. The other guy seated in the room escorted me out, who I found out as we were talking was the recruiter who called me. I came in for an interview, not an argument with the director.