The switching matrix of a PBX performs the same job as does an operator at a manual switchboard or a common control central office switch. These computerized electronic switches are used to perform routine, as well as unique, functions that simply weren't practical or even possible with electromechanical switches. We're all familiar with key telephone sets, whether we know them by name or not. Systems with PBXs and key sets have a great deal of flexability in planning for their needs because they can set up their codes to accomplish the functions needed in their particular situations. In fact, the PBX can be programmed so that each individual extension within a system can take advantage of features applicable to its own business needs.
Some features automatically handle incoming telephone calls.
Automatic call waiting not only holds calls made to a busy extension until the extension is free, but also signals the person being called that a call is waiting and informs the caller that he is on hold. Another example is automatic call back, which allows a caller who reaches a busy line to ask the PBX to return his or her call when the line is free. Still other features provide services such as night telelphone answering, telephone traffic monitoring, and network or hot-line connection. These examples are but a sample from the features possible with computerized PBXs. Then you will hear a dial tone.