Class-5 telephone switch
（重定向自End office）
A class-5 telephone switch is a telephone switch or telephone exchange in the public switched telephone network located at the local telephone company's central office, directly serving subscribers. Class-5 switch services include basic dial-tone, calling features, and additional digital and data services to subscribers using the local loop. Class-5 switches were slower to convert from circuit switching technologies to time division multiplexing than the other switch classes.