Vehicular ad hoc networks (VANETs) have recently received considerable attention. In such networks, mobile nodes are spontaneous and uncoordinated associations of vehicles equipped with 802.11-based hardware, and change their positions dynamically. VANETs applications require data, voice and video transmission. However, Voice over IP (VoIP) may provide good services through VANETs platform. It may cover many application scenarios range from safety to comfort related services. In this paper, our approach is based on VoIP over VANETs (VoVAN) by means of simulation. For this task, a performance evaluation of various voice CODECs and its impact on quality of service metrics will be analyzed, focusing on inter-vehicular voice communication. To achieve good results, we use mobility information obtained from vehicular traffic generator which is based on the real road maps of an urban environment. Results of the simulations are presented in terms of both network level (such as E2E delay) and user level (Mean Opinion Score) metrics. This performance evaluation showed that G.723.1 CODEC worked well in the urban VANET environment.