Abstract: The present trunk line exchange system is capable of coping with the busy hour calls without falling into congestion by executing re-distribution of the number of communication lines to the busy region from the quite region, which results in yielding efficient utilization of the communication lines. The system is also capable of avoiding the congestion of the exchange system, since it is not necessary to conduct a series of operations such as recalls/alternative line processing.

Abstract: An automatic facsimile signal analyzing system includes a switch unit, a service trunk, a signal identification trunk, a facsimile communication determination unit, and a control unit. The signal identification trunk restores a facsimile control signal from a modulated and encoded facsimile signal on the set speech path and performs collection of communication state information and detection of a start of facsimile communication on the basis of the restored facsimile control signal. The facsimile communication determination unit permits an operation of the signal identification trunk when the classification result from the service trunk represents a type other than the voice signal and analyzes the communication state information from the signal identification trunk.

Abstract: A circuit board comprises a rigid metal substrate, a conductive metal layer formed into a predetermined circuit pattern, and a resinous layer interposed between the metal substrate and the metal layer for electrically insulating and bonding the metal substrate and the metal layer, the conductive metal layer having an elongation at break of not less than 15%, and the resinous layer comprising a first resinous layer having a volume resistivity of not less than 10.sup.10 .OMEGA.. cm, and a second resinous layer having an elongation at break of not less than 100%. The circuit board has a desired dielectric strength between the metal substrate and the conductive metal layer and can be bent without resulting disconnection in the metal layer or the like.