ESSAY: What are possible barriers to effective communication over the phone?

Communication over the phone has a lot of advantages compared with face-to-face direct communication. The first one is that phone communication is quick and instant. We do not have to go to their place and even we can call someone who is in a foreign country. The second advantage is that we can focus on our main topic. However their are some downsides. First, over the phone, we can not use non-verbal methods such as gesture and facial expression. We often can catch more information from facial expressions than verbal ones. In addition, due to its instant feature, we could be less cautious when we talk over the phone. We often say something unthinkingly that hurts listener\'s feeling. Another negative thing is that it might annoy other persons around us when we call in a public area such as in a subway or in a shop. It could result in not only annoyance but also eavesdropping.