Nowadays, many types of Voice over Internet Protocol (VoIP) are used to provide audio communication and multimedia sessions over Internet Protocol (IP) networks, any number of people connected together in a network that provides Internet Protocol(VoIP) can make multimedia communications easily. Network simulation has frequently been using to determine network protocols and models' rationality and reliability before practical implementation. Several kinds of studies were carried out on voice efficiency over different WLAN networks, among these experiments and research, finding a better signaling protocol for communication by evaluating and analyzing the performance of the protocols, such as the most commonly used protocols (SIP) and (H.323). This paper provides a comparative study of the performance of the two protocols that are most widely used over the same IEEE 802.11a wireless network using QualNet simulator. The study was performing on the data packets for both initiator & receiver for both protocols, to evaluate the performance for five metrics to be measured: Session total Bytes, Establishment time, Sent, total Bytes received RTP Average End to End Delay and Overall Throughput. The results illustrate SIP protocol outperforms H.323 by overall throughput with an unnoticeable delay at the same time taken for the simulation. Hence its superior provides better recommendations in audio connectivity and multimedia sessions.