What should I tell my boss?

I run a reception desk in an office. Everyone in the office is constantly going outside to smoke. But because I am answering phones, I'm not able to do that. I normally smoke a couple times a day. Today I was on a smoke break while someone else was answering the phone and a manager from another dept accidentally got a call that should of went elsewhere. She blew up and told me I shouldn't be smoking. We don't even have a damn Employee Book!!!! What should I say to my boss when he calls me in the office tomorrow about this? (He was off today) He always says that he holds me at a higher standard, because he expects more, but I shouldn't have different rules than everyone else. There is no black and white for this b/c we have no handbook. Should I just suck it up and watch everyone else get their nicotine pleasantly, or demand to be treated the same?