电话号码升位方案的选择张选择升位方案是升位改号中的一个主要问题。近１０年来，我国市话网容量不断扩大，升位改号频繁。过去，我国的升位改号一般都采用逐步升位的方法，１９８９年上海首先全市一次升位，采用单局号升位法，后来，天津又创造了双局号升位法。目前大多... The choice of a phone number to lift the program Zhang choose to lift program is a major problem in the lift change number. In the past 10 years, the capacity of local telephone network in our country has been constantly expanding, and frequent revision and revision have been frequent. In the past, our country has generally adopted a gradual upgrade or change the way the number of bits, in 1989 the city of Shanghai in the first rise of a single, using a single number or bit-up method, and later, Tianjin has created a double-number law. Mostly ...