A packet communication system of this invention includes a user access device at a user point for providing a user with connectivity to a plurality of carriers, carrier communication networks linked to the user access device, and a carrier management network which controls and manages the user access device and communication devices. A communication device receives a control frame-inserting command from the carrier management network, and sends a control frame containing therein control frame transfer information that indicates which one of termination and send-back processing is performed at a destination device. In response to receipt of the control frame, a user access device that is the destination of this frame extracts therefrom the control frame transfer information. If this information indicates the termination then perform termination; if send-back, add thereto a header necessary for the send-back and then transfer it.