| 摘要 |
An automatic telephone exchange, such as a PABX, includes a number of group control units (GCU1 to GCU4) each of which is a simplified version of the system of U.S. Pat. No. 4581733. These are connected via respective PCM highways to a central switch, which is an electronic time space switch, and a central controller. The central controller does the major part of the call setting and control, all calls being set up via the central switch. |
