The invention relates to a wireless communication device that is coupled to an energy source, such as a battery, capacitor, or solar cell. One method embodiment includes storing a value as a state in a first memory cell and as a complementary state in a second memory cell. Preferably, the digital phone is able to encrypt and decrypt data, so that all of the data transmitted between the phone and the financial authority can be in an encrypted form. In one embodiment, the contact surfaces of the silicon contact are plated in gold and are planar. A video data reception device 108 uses the notified session information or the confidential information so as to select encoded data from the normally received encoded data from at least one session, according to the video quality, and decode it.