International Academy Publishing (IAP)
In this paper, the performance of Voice over Internet Protocol (VoIP) for five different codecs, using IPv4 and IPv6 is established. The codecs tested were G.711.1, G.711.2, G.723.1, G.729.2 and the G.729.3 codec. The operating systems used were; Windows XP, Windows Vista and the Windows 7. Parameters considered for these performance tests were RTT (Round Trip Time), jitter, and throughput. The results arrived at aid a user organization of VoIP with the preferred choice of the IP version stack to be used for a given operating system.