Japan has two types of mobile phones--cellular and PHS (personal handyphone system)--distinguished by the type of signals they operate on. Over the last few years many features have been added to these phones, such as answering services and functions that allow the user to send and receive text messages. In addition, the prices of the units and phone rates have dropped so low that one out of every three people in Japan now owns a mobile phone. The PHS, less expensive than the cellular, tends to be the phone of choice for middle and high school students. The sounds for incoming calls used to be limited to a standard ring, but a few years ago some slightly more musical varieties became available. Since many of these phones recognize the incoming caller's number, users can program different melodies for different callers. More recently, programming the melodies of one's favorite tunes has become the rage among young people. There are now dozens of manuals and books on sale that explain how to compose melodies or provide long lists of numbers that users can input into their phones to create the melody of their choice. One series has sold about 3.5 million copies, and in large bookstores there are entire sections devoted to these books. For those who find it too boring or difficult to program their own melodies, one PHS company offers a service that sends melodies of the latest hits or seasonal songs directly to the users' phones. PHS owners can call the company from their phones and simply request their desired songs. This service has become very popular, receiving around 500,000 calls each month. Many young users change these ring melodies depending on their state of mind, choosing inspiring songs when they are studying for an entrance exam, or songs with a graduation theme when the end of the school year draws near. Today, on any street corner in Japan, one is likely to hear a variety of melodies singing out from mobile phones: everything from television show theme songs and hits by popular artists to even the hugely popular "Dango Sankyodai" (Three Dumpling Brothers) song that is taking the country by storm. Photo: Now there is just as much variety in how phones ring as in how they look.