Do Your Research: Have a proper Research work: Never underestimate a telephonic interview. You have the whole internet at your fingertip; there is no reason for not getting your work done. Think about the occupation you have applied for also, about the organization and everything to sound better and intelligent.
Be Clear and Logical: Be clear and polite in your discourse. If you are nervous or have a quick discourse, try to stab at backing it off. Correspondingly, if you can't comprehend your questioner, don't hesitate in asking him to repeat the question. You should talk sense and should be intelligent while replying.
Don’t Talk at a Noisy Place: It is important Avoid being at noisy places during your telephonic interview. Go to a silent place to have a conversation.
Don’t Lose Track: Always stick to the asked questions. Don’t lose the track and sense of your answers by digging deep in the conversation.
Keep your mobile phone charged: Make sure one thing beyond any doubt that your phone is sufficiently charged for a long discussion. It would give you a bad impression if you give an excuse of having a low battery during your discussion.
Don’t Argue: Never be argumentative. If they tell you that your answer to something is wrong but you know you are right, don’t argue, instead explain yourself calmly and politely.
Act Smart: If your interviewer is asking some about a question related to your field, avoid from writing or turning pages of a book. Obviously, it is always best to do your homework in advance.