Abstract: A method of accessing a communication system and a communication device for performing the same are disclosed. The method includes transmitting, by the communication device to a node of the communication system through a communication link between the communication device and the node, a registration request to register with the communication system, transmitting, by the communication device to the node, a request to disconnect the communication link, when receiving from the communication system a registration response in response to the registration request before receiving an authentication request from the communication system.

Abstract: A method of accessing a communication system and a communication device for performing the same are disclosed. The method includes transmitting, by a communication device to a node of a communication system through a communication link between the communication device and the node, a request to negotiate basic capabilities for communicating with the node, receiving, by the communication device from the node, a response to the request to negotiate basic capabilities, and, transmitting, by the communication device to the node, a request to disconnect the communication link, when the response to the request to negotiate basic capabilities indicates that the node does not support authentication.