PURPOSE: To attain the transmission even in the B-channel busy state by providing a means detecting the B-channel busy state in a network and sending communication information in a D-channel packet automatically.

CONSTITUTION: In the case of B-channel busy state, a B-channel busy state of a line is detected by a D-channel call control circuit 5 and when the busy state is detected, the call control for starting the use of B-channel is finished to apply call control for D-channel packet use start and a packet start signal is outputted to a packet selection circuit 4. In this case, the packet selection circuit 4 outputs a select A signal and a select B signal switching the connection of a selector A2 from the position of a B-channel control circuit 3 to the position of a D-channel packet control circuit 6 and switching a selector B7 from the position of a D-channel call control circuit 5 to the position of the D-channel packet control circuit 6 through the input of the packet start signal. Thus, even in the case of B-channel busy state, a video signal is able to be sent.