Voice over Internet Protocol (VoIP) is important technology that’s rapidly growing in the wireless networks. The Quality of Service (QoS) and Capacity are two of the most important issues that still need to be researched on wireless VoIP. The main aim of this paper is to analysis the performance of the VoIP application in wireless networks, with respect to different transport layer protocols and audio codec. Two scenarios used in the simulation stage. In the first scenario VoIP with codec G.711 transmitted over User Datagram Protocol (UDP), Stream Control Transmission Protocol (SCTP), and Real-Time Transport Protocol (RTP). While, in the second scenario VoIP with codec G.726 transmitted over UDP, SCTP, and RTP protocols. Network simulator NS2 is used in all scenarios. In addition, several QoS criteria such as throughput, end-to-end delay, jitter, and packet loss has been considered to evaluate the performance of VoIP. The result shows that SCTP throughput performs better for VoIP application when compared to other protocols and also approved that VoIP has less end-to-end delay and jitter over RTP and UDP contrast with SCTP.