|
The Mobile Telephone Service (MTS) is a pre-cellular VHF radio system that links to the Public Switched Telephone Network (PSTN). MTS was the radiotelephone equivalent of land dial phone service. , only rural and wilderness areas were still using the system. The Mobile Telephone Service was one of the earliest mobile telephone standards. It was operator assisted in both directions, meaning that if one were called from a land line the call would be routed to a mobile operator, who would route it to one's phone. Similarly, to make an outbound call one had to go through the mobile operator, who would ask for the mobile number and the number to be called, and would then place the call. This service originated with the Bell System, and was first used in St. Louis on June 17, 1946. The original equipment weighed , and there were initially only 3 channels for all the users in the metropolitan area, later more licenses were added bringing the total to 32 channels across 3 bands (See IMTS frequencies). This service was used at least into the 1980s in large portions of North America. 〔 Regis J. Bates, Donald W. Gregory ''Voice & data communications handbook'' McGraw-Hill Professional, 2007 ISBN 0-07-226335-0 page 193〕 On October 2, 1946, Motorola communications equipment carried the first calls on Illinois Bell Telephone Company's new car radiotelephone service in Chicago.〔( Motorola First Car Radio Telephone )〕〔(History of Car Telephones 1946-1953 )〕 Due to the small number of radio frequencies available, the service quickly reached capacity. MTS was replaced by Improved Mobile Telephone Service (IMTS), introduced in 1964. ==Channels== () uses 25 VHF radio channels in the United States and Canada. The channels are identified by pairs of letters taken from positions on a North American telephone dial that, when changed to digits, form (for 12-channel mobile sets) 55, 57, 95 and 97. In the 1960s plan, the VHF high-band allocations provided for 11 channels in the United States: JL, YL, JP, YP, YJ, YK, JS, YS, YR, JK and JR. In Canada, two additional channels were available: JJ and JW. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Mobile Telephone Service」の詳細全文を読む スポンサード リンク
|