Cleveland Abbe
In order to compile his information, Abbe required a time-keeping system that was consistent among the stations. To accomplish this he divided the United States into four standard time zones. He published, in 1879, a paper titled "Report on Standard Time". In 1883, he convinced North American railroad companies to adopt his time-zone system. In 1884, Britain, which had already adopted its own standard time system for England, Scotland, and Wales, helped gather international consent for global time. In time, the American government, influenced in part by his 1879 paper, adopted the time-zone system.
North American Numbering Plan expansion
The North American Numbering Plan was devised in the 1940s, implemented in 1947, and has provided customer direct-dialed long-distance telephone service since 1951. Occasionally, the growing demand for telephone numbers has mandated certain changes in the format of telephone numbers and method by which they are allocated to telephone companies. Instead of expanding the size of telephone numbers, as implemented in many countries outside North America, the NANP was designed as a closed numbering plan, having a fixed number of digits, three digits for the numbering plan area (NPA) code and seven digits for telephone numbers that are unique in each NPA. The telephone number was further distinguished as consisting of three digits that identified each central office and four digits for each subscriber station connected to the same central office. From 1947 to c. 1960, the initial two digits of the central office code were mapped to two letters of an often locally significant name, the central office name or exchange name. However, this scheme, practiced since its invention by W. G. Blauvelt of AT&T in 1917, prevented the use of numerous digit combinations that could only be associated with unpronounceable or, at best, confusable names. All-number calling removed these restrictions and permitted the phasing out of exchange names. Central office codes were initially still restricted from using digits "0" and "1" in the middle position, which provided a distinction to area codes, which always had "0" or "1" in the middle position. This last restriction was removed by 1995, with the phase-out of electromechanical switching systems by programmable electronic switching systems (ESS).