PURPOSE: To improve the processing speed of packet communication by allowing a packet logic multiplexer to set information speed based on an idle line capacity so as to inform it to a packet terminal and allowing the packet terminal to designate the informed information speed to apply calling request.

CONSTITUTION: When a packet terminal PT1 (X25CR) makes a calling request by a packet (in compliance with the CCITT recommendations X.25), a packet logic multiplexer (IPMX) 3 analyzes an I(X25CR) packet to check the incoming call information speed and checks whether the information speed is within the idle line capacity in a RAm 12, and retrieves the maximum information speed within the idle line capacity among the information speed usable for the packet terminal PT1 registered in advance in the RAM 12, sets the result to the calling information speed in the I(CRR) packet for the transmission. The packet terminal PT1 analyzes the I(CRR) packet, extracts its calling information speed and sets the information speed to the incoming call information speed in the I(X25CR) packet and sends the result.