As the PTT's subscriber base topped two million at the beginning of the 1970s, the country introduced a new, seven-digit phone numbering system. By then, the PTT was also becoming interested in a number of new technologies. In 1970, the PTT led a work group, including a number of prominent Swiss telecommunications players, in an effort to create an integrated digital telecommunications network (IFS). Originally intended to be rolled out by the middle of that decade, the first IFS exchange did not become operational until 1986.