Office classification

Office classification: Prior to divestiture, numbers that were assigned to offices according to their hierarchical function in the U.S. public switched telephone network.

Note 1: The following class numbers are used: Class 1: Regional Center (RC) Class 2: Sectional Center (SC) Class 3: Primary Center (PC) Class 4: Toll Center (TC) [Only if operators are present; otherwise Toll Point (TP)] Class 5: End Office (EO) [Local central office]

Note 2: Any one center handles traffic from one center to two or more centers lower in the hierarchy. Since divestiture, these designations have become less firm.

Source: from Federal Standard 1037C