Mobile communication is one of the fastest growing sectors of the telecommunication industry. Mobile users can make and receive calls while they are moving independent of time, location and network access. The Global System for Mobile communication (GSM) is a Pan-European digital cellular mobile system supporting widespread roaming and personal communication services (PCS) in a worldwide wireless communication network. However. wireless mobile systems are more vulnerable to fraudulent access and eavesdropping. Although the authentication process in GSM is giving a reasonable security level, it is overloading the network with significant signaling traffic and increasing the call set up time. The signaling load and the authentication delay are of particular importance and become the subject of widespread research interest. In this paper, we will study and analyze the GSM privacy and authentication protocols, and propose nerv authentication protocol with less signaling traffic and better call set up time, that can be used in GSM networks.