When you ask your father for permission to visit your friend's house, he could say yes or no. In oral communication there is a possibility of immediate response. This makes
speedy interaction and immediate feedback possible. This is the biggest advantage of oral communication.
Another advantage is that the speaker can observe the listener's reaction to what is being stated. For instance if someone comes to you on the date of your exam results and tells  you that you have passed, your reaction to the message will show that you are happy.
Similarly if someone tells you that your friend fell down and had an injury you will be shocked and the person who gave you the message will notice your shock.

How would you feel if your favorite cinema star saw you somewhere and spoke to you  voluntarily? Yes, you would be happy! And you would also feel very important is it not?
Oral communication can therefore give a feeling of importance.

The disadvantage of oral communication is that it does not always save time. It is not possible for the Prime Minister to speak to the people at Red Fort every day. It will cost a lot in terms of money, time, and other important resources. People have to meet each other all the time to communicate orally. This is impossible.