1. A method for deriving presence information of a mobile device at a presence node in a wireless system, the method comprising: analyzing a message sent from the mobile device to determine whether a message type is interactive or non-interactive, the message type being interactive when message generation is user-initiated and the message type being non-interactive when the message is automatically generated by the mobile device, the message including a time value indicating an amount of time since the mobile device was actively used, the message including added information, the added information being a single bit to indicate if the message is interactive or not interactive; assigning a connected state to the mobile device when the message sent from the mobile device is determined to be a non-interactive message and when the time value indicates that a predetermined amount of time has elapsed since the mobile device was actively used, the connected state indicating that the mobile device is currently connected to the wireless system but has not been actively used for at least the predetermined amount of time; assigning an active state to the mobile device when the message sent from the mobile device is determined to be an interactive message; and assigning a disconnected state to the mobile device when no messages are sent from the mobile device during a timeout period.