2. Never ask “What company is this?” again:  It is always advisable for you to research well about the company before facing the interview. You should know the company well before interviewing, although it is okay to ask once, ‘what company is this?’ It can irritate the interviewer if you ask it again. If you do so, he/she may think that you are not serious about the job as you have not taken the minimal pain to research about the organization before the interview.  

3. Putting the interviewer on hold: During telephonic job interviews never try to put your interviewer on hold as he may get annoyed and think that you are not much interested for the offer. He /she may have a negative impression on you and may think that you are not a sober person and that you are not valuing his time. Of course, never ask him to reschedule the meeting.