Abstract: There is disclosed a system for modifying a path taken in a transmission network system comprising first and second nodes. The first node routes a signal transmit to a first line to a second line. The second node checks the quality of the first and second lines. After checking that the second line is of good quality, the second node selects the second line. The first node stops entry of signals into the first line. Thus, modification of the path is completed.

Abstract: An order wire accommodation system comprises four interface boxes each of which has the same order wire interface section as the others. The order wire interface section has a circuit which digitally adds order wire signals of the transmission lines from two ports and the order wire signals which interface with the other interface boxes or a telephone through the other two ports. Each output from the order wire interface section is a sum of all the order wire signals inputted except for those of the order wire interface section itself. Because of a provision of two ports which interface externally, the interface boxes can be cascaded connected to one another, by which order wire communications among all the transmission lines accommodated in the interface boxes become possible. Further, the order wire accommodation system can be minimized and be simplified.

Abstract: In each low-rate interface 1, a clock/frame pulse signal 16 is separated from a signal 11 outputted from a high-rate interface and coupled through a phase controller 6 for clock substitution in a clock substituting circuit 5. The phase controller 6 sets a phase delay as a result of design when making evaluation such that the phase of a signal 13 inputted to an exchanger 7 is coincident with the phase of its output signal 12. Thus simplifying the clock supply to low-rate interfaces in a multiplex transmission system, in which housings of a high-rate interface and the low-rate interfaces are physically separate from one another.