In a packet-switched communications network, each of a plurality of terminals sequentially transmits control packets in response to a request for call before sequentially transmitting message packets. A switching node of the network is responsive to the control packets for establishing first and second logical channels through the network. Message packets are propagated through the first logical channel. The established logical channels are monitored to detect an abnormal condition. In the event of an abnormal condition in the first logical channel the message packets are re-routed to the second logical channel.