The invention provides methods of purifying Rebaudioside D from the Stevia rebaudiana Bertoni plant extract along with Rebaudioside A. The provided Internet cordless phone includes an Internet phone station for processing an Internet phone protocol and cordless handsets for processing audio codec and user interface, wherein the Internet phone station and the cordless handsets are connected by Bluetooth asynchronous connection-less links. A pulse generator that is connected to the electrodes delivers electrical impulses to sympathetic nerves located within the posterior longitudinal ligament of the lumbar spine and outer posterior annulus fibrosus of the intervertebral disc. The teeth are inserted through the through holes.