tailieunhanh - The Cellular Connection 1 phần 4

Đầu dịch vụ điện thoại di động được giống như sử dụng một đài phát thanh hơn là điện thoại. Bạn nói vào microphone hay các thiết bị cầm tay đặc biệt, và tiếng nói từ đầu kia của kết nối thường đến thông qua | The Cellular Connection A Guide to Cellular Telephones Fourth Edition. Robert A. Steuernagel Copyright 2000 John Wiley Sons Inc. ISBNs 0-471-31652-0 Paper 0-471-20340-8 Electronic 3 THE BUSINESS OF CELLULAR PHONES The business of cellular phones is a big one. Although cellular phone companies must make a large initial investment the potential for an enormous return makes it certain that there will be no shortage of firms to service the cellular user. WHERE CAN YOU GET CELLULAR SERVICE Cellular service was deployed beginning in 1983 in order of city population with licenses for the largest cities awarded first. While some potential users have had to wait for service in smaller cities in 1992 the last tertiary markets established commercial service. Now cellular service is available in all populated areas in the United States including Alaska and Hawaii Canada Mexico and Puerto Rico. Only the most desolate wilderness areas may not have complete coverage. HOW LICENSES WERE GRANTED WIRELINE AND NONWIRELINE COMPANIES The Federal Communications Commission FCC which controls and watches over the cellular communications industry is responsible for issuing the licenses required to operate cellular systems. 19 20 THE BUSINESS OF CELLULAR PHONES To encourage competition the FCC decreed that provision be made for each area to be serviced by two cellular phone carriers one a wireline and the other a nonwireline service. The wireline carrier is usually affiliated with the organization that already provides conventional telephone service in the area your local telephone company. Such companies are usually already involved in mobile communications in areas other than cellular and frequently bear a name similar to that used by their parent organizations. The wireline carrier in an area was assigned the B block of frequencies see Figure . The competitive component required by the FCC in the cellular market was provided by another sort of company a nonwireline service. This .