资料来源 : Free On-Line Dictionary of Computing

Central office exchange service
     
         (Centrex) A {PBX} service providing
        {switching} at the {central office} instead of at the company
        premises.  Typically, the telephone company owns and manages
        all the communications equipment necessary to implement the
        PBX and then sells various services to the company.
     
        (1999-10-27)