| 释义 |
Class 1 In the traditional public switched telephone network (PSTN) hierarchy, a regional toll center. The 10 Class 1 offices that existed prior to the breakup of the Bell System served to interconnect Class 2 offices, or sectional toll centers. At the end of 2001, seven remained in the United States, and two in Canada. See Figure C-3. See also Bell System, Class 2, and PSTN. |