I am sorry, I didn't think you would dial to me on phone. I am black out in my mind and don't know what you have said. Sorry! 注意:打电话已经是说话以前发生的事,所以要用过去时态,而“空白”和“不知道说什么”却是此时此刻的状态,用现在时是当然的。
I was sorry faithfully. I had never expected that you might phone me. My cerebrum was an absolute blank. So that I had no idea actually about what you said. Consequently, I really apologize it.