The second layer (Data Link) has the function of giving the physical address of the device connected to the network and this address is a constant that does not change by changing the location of the device on the network and can be likened to the serial number of the cellular device (Serial no.), Which remains constant regardless of the cellular network that works on the device. This layer also checks for errors of received information (Cyclic Redundancy Check “CRC”). This layer is also evaluated with an important function (media access control) in the sense of setting up a mechanism to control network selection by parties' It is understood that the network has several users (parties) communicating with each other through the network, so it is necessary to find ways to ensure that the shared network is used by all parties without affecting the other.