tandem central office
tandem central office[′tan·dəm ′sen·trəl ′ȯf·əs]
A telephone office that makes connections between local offices in an area where there is such a high density of local offices that it would be uneconomical to make direct connections between them. Also known as tandem office.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.