and the selector 110 select the first voice signal 114 from the cell disassembling section 102 if the detection signal 120 indicates that the synchronous signal is detected therefor the selector 110 selects any one of the first voice signal 114 from the second cell disassembling section 102 and the second voice signal 119 from the coder 111 in accordance with the control signal 121 from the controller 107 and then sends the selected signal to the cell assembling section 19 the address indicator 106 generates an address indication signal 122 for indicating an address of a transmission destination in accordance with the detection signal 120 from the detector 108 this address indication signal 122 is sent to the cell assembling section 19 the cell assembling section 19 is composed of a first cell assembling section cla 112 and a second cell assembling section cla 109 the first cell assembling section 112 assembles a second signaling signal 117 supplied from the second multiplexer demultiplexer 13 into a signaling cell the second cell assembling section 109 assembles the first voice signal 114 or the second voice signal 119 sent through the selector 110 into a voice cell at this time an address indicated by the address indication signal 122 from the address indicator 106 is set to the voice cell as a transmission destination address next the operations of the voice relaying apparatus having the above mentioned structure will be described below with reference to fig2 to 4 hereafter a first case in.