With the general trend towards ubiquitous access to networks, more users will prefer to make voice calls through the Internet Voice over IP (VoIP) as the application which facilitates voice calls through the Internet will increasingly occupy more traffic. The growth of delay sensitive traffic that requires special quality of service from the network will impose new constraints on network designers who should wisely allocate the limited resources to users based on their required quality of service. An efficient resource allocation depends upon gaining accurate information about the traffic profile of user applications. In this paper, we have studied the access level traffic profile of VoIP applications and proposed a realistic distribution model for VoIP traffic. Based on our model, we have introduced an algorithm for resource allocation in networks. It is shown that using our algorithm will enhance the delay and utilization performance of the network.