The purpose of this study is to develop a network performance test system which measures jitter and latency of low bit-rate voice over IP traffic. The system is capable of making accurate and precise measurements in a Windows 2000 Operating System environment. Precise, GPS-synchronized timing is achieved with the use of a dedicated bus-level time processing card. Packets are timestamped in a protocol driver for versatility but can be timestamped in a network card driver for more accurate timing. The overall error associated with the system's measurement was assessed and was found to be less than 90s in the worst case and less than 10s in the best case. Example network tests such as broadband Internet service, wireless LANs, and wireless data service are analyzed. Concatenated networks were tested as well. The work is applicable to not only voice over IP systems, but any real-time, low bandwidth systems.