【B1】 【B5】

Once regarded as an expensive status symbol, the cellular telephone has become a popular crime-fighting and safety tool for drivers. Every month, people with car phones make 600,000 calls to emergency numbers, reporting not only drunken driving but also such crimes as drug deals, burglaries and car jackings. "They are our eyes and ears," says Dennis Martin, executive director of the National Association of Chiefs of Police.
    Some car phones are installed permanently, drawing power from the vehicle’s battery. Others are portable, powered by the car’s cigarette lighter or by an internal, rechargeable battery. But all operate the same way. Dialing a cellular phone sends a radio signal to the telephone company tower covering that geographic area, or cell site. When a driver begins moving out of one cell site, a telephone company computer senses the weakening signal and automatically passes the call to the next tower.  With about 13,000 towers in operation, 97 percent of the population lies within range of cellular service. When car phones first appeared, some police officials worried that drivers using them would not pay attention to the road and would get in accidents. In fact, the phones are making the roads safer, particularly against the danger of drunken drivers. And police are now cooperating with initiatives involving cellular phones.