Voice over IP Protocol is an important Internet voice connection, characterized by high quality of service. In this work, we will assess how today's Internet service matches its expectations by examining the performance of the Voice over IP protocol and its quality of service. We have relied on the method of selection of encoders first within some parameters to obtain the simulation result of the comparison and analysis (QoS). Which we adopted on VoIP protocols in the case of multiple users with three algorithms for the symbols, and after determining the problem in this range, we took a number of factors into account due to their impact on sound performance, such as jitter and Delay. This action simulates three of the most common encoders (analog audio conversion and packet compression), G.711, G.723.1 and G.729. The main objective is to achieve high-quality sound performance by making the appropriate decision in the choice of sound encoder.