NAS layer is utilized to deal with the foundation of communication sessions and for keeping up with constant interchanges with the user equipment as it moves. The layer upholds signalling messages between the CN and UE. The NAS is characterized in contrast to the Access Stratum which is liable for conveying data over the wireless portion of the network. It is a protocol for messages passed between the User Equipment, otherwise called mobiles, and Core Nodes that is gone straightforwardly through the radio network.