Dissertation (MSc Telecommunication Engineering)Vehicular Ad-hoc Network (VANET) is a subclass of Mobile Ad-hoc Network where by vehicles on the road network are able to exchange data. Many automobile manufacturers make vehicles which are pre-equipped with devices such as Geographical Position System (GPS), Radar and Lidar, Bluetooth, Onboard LTE module. Therefore, in the future, Self-driving cars will be available in many countries and voice communication between vehicles will present many services ranging from safety to non-safety. Several researches have been conducted to evaluate the impact of voice CODECs in MANET. However, the results in MANET cannot be applied in VANET due to the unique characteristics such as high mobility of vehicles, frequently disconnection of network, rapid topology change and high node density. In this study, the impact of IDM-IM and FTM mobility models on the performance of G.711, G.723.1, G.729A, GSM.AMR and GSM.EFR voice CODECs was investigated. VanetMobiSim 2.2 and NS-2 were used as traffic simulator and network simulator respectively. The simulation results were presented using four performance metrics (average End-to-End delay, average jitter, packet delivery ratio and Mean Opinion Score). The results showed that G.729A provides good voice quality under IDM-IM mobility model. This is due to fact that, G.729A provides acceptable delay, packet delivery ratio and MOS as recommended by International Telecommunication Union for packet-based voice communication.