A Class-5 switch provides telephone service to end customers locally in the exchange area, and thus it is concerned with "subscriber type" activities: generation of dial-tone and other "comfort noises"; handling of network services such as advice of duration and charge etc.
Urban areas with extensive underground plant tend to keep the classic class-5 office architecture.
The DDD program involved installations of large numbers of new 5XB crossbar switches in the 1950s and 1960s.
Principal European products include Ericsson AXE telephone exchange, Siemens EWSD and Alcatel-Lucent S12 and E10.
In the 21st century, US and European service providers continued to upgrade their networks, replacing older DMS-10, DMS-100, 5ESS, GTD-5 and EWSD switches with Voice over IP technology.