While talking on the telephone often you ask the listener - "Are you Listening?" If there is no sound of response such as 'hmm', 'yes', 'please go ahead', 'I understand', etc. you tend to feel that your words are falling on deaf ears. More so when you are negotiating on the telephone.
But what happens when you talk face to face?
The significance of your words is reduced to just 10 to 15%. 'How you say it?' - becomes more important than what you say. Even when you are articulate the efficacy of your words will not go down unless you compliment your words with voice modulation.
Modulation is your ability to bring variance in Pace, Pause, Pitch, Emphasis on the keywords and the Tone.
Further, you body language* too is extremely important for making the communication convincing and effective.
Attentive listening to others is the key to build good relations. Listen to others and they will listen to you!