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 protoco
l 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.
The process of transfer a speech signal by high confidentially and as quickly as possible through the Internet needs to develop compression and encryption technology for a speech signal, so as, to reduce its size and make it understandable to persons
not authorized to listen to.
A system was designed to encrypt the voice over Internet Protocol (VoIP) and use compression technique for the purpose of reducing the size of data and send it over the network, (A_law PCM) algorithm was used the to compress audio data. Then algorithms of Triple Data Encryption Standard (TDES) and Advanced.
Encryption Standard (AES) were applied. A new encryption algorithm was proposed based in its work on the block cipher encryption system called the Direct and Reverse algorithm, which based on three basic steps, firstly expand the initial key, secondly direct the encryption of each round in one direction, and finally substitute (Bytes) as used in the Compensation Box in AES algorithm by making it moving. In general compression ratio was calculated and it was (50%) and the results of the correlation coefficient for the proposed algorithm was compared with the results of (AES, TDES) algorithms.
