Provided is a mobile communication system capable of reducing interference in uplinks and downlinks to achieve excellent communication quality. The display unit includes a plurality of organic electroluminescent devices, each including an organic layer portion including at least a hole-transport layer and a luminescent layer which are stacked each other, and two electrodes sandwiching the organic layer portion. A snoop queue is associated with the predetermined bus master for storing a plurality of snoop requests and selectively storing for each snoop request an indicator of a synchronization request that indicates a synchronization operation is to be performed by completing any previously issued snoop requests prior to or concurrently with completion of the synchronization operation. Once the audible tone is detected, a web browser is launched and the tone or decoded product identifier information associated with the tone is transmitted to an ARS on the network.