Cell Phones compatible with Japan’s mobile digital TV service have reached the 20 million mark in less than two years since the launch of the service. The Telecommunications Carriers Association said that the 20 million mark was reached in December of 2007, thanks to the shipment of over 1 million handsets during the month.

OneSeg, the digital TV service launched on April 1, 2006, delivers a QVGA (320 pixels-by-240 pixels) resolution simulcast of Japan’s terrestrial TV networks at no cost to the viewer. Cell phone makers have been able to build recording functions into handsets because the broadcasts don’t carry any copy protection software. Mobile phones are able to pick a TV show from an electronic program guide sent with each channel and set the phone to record the show into memory for later viewing.

Cell phones are not the only devices to utilize this technology. Laptops, music and video players, electronic dictionaries and even car navigation systems are able to function as OneSeg receivers. OneSeg is favored in portable devices because the processing speed needed to handle the OneSeg signal is much lower than the speed needed for a conventional high-definition digital TV signal. Standard terrestrial HDTV needs a receiving device that can handle around 20M bps, whereas the maximum OneSeg data rate in about 416k bps.