this invention provides a device , method and system for implementing an echo control on hand - free phones , including an echo eliminator as a primary component . the method in use is listed as follows . first of all , local speech signals on a sending channel as well as remote speech signals on a receiving channel are sampled . then call status of a current network is determined based on energy of the obtained remote and local speech signals samples . finally , a corresponding echo control treatment to the speech signals traveling through the sending channel according to the resulting call status is given . as a result , the echo in a digital hand - free communication system can be efficiently eliminated .