A sound signal processing device comprising: a microphone terminal to which a sound signal derived from sound received by a microphone is input; a loudspeaker terminal from which a sound signal directed to a loudspeaker is output; a first input terminal to which a sound signal from an other device at a proximal-end is input, wherein the term proximal-end refers to a signal that does not pass through a network; a first output terminal from which a sound signal directed to the other device is output; a distal-end input terminal to which a distal-end sound signal is input via a network, wherein the term distal-end refers to a signal passing through the network; a distal-end output terminal from which a sound signal directed to the network is output; a detector configured to detect a connection status of a subject device to the network and a connection status of the other device to the network, the subject device being a sound emission-reception apparatus and the other device being a proximal-end sound emission-reception apparatus other than the subject device; a path establisher configured to establish at least one signal path from at least one of the microphone terminal, the first input terminal, or the distal-end input terminal, to at least one of the loudspeaker terminal, the first output terminal, or the distal-end output terminal, the path establisher being established in a digital signal processor, DSP,; and a path indicator configured to indicate to the path establisher a signal path that is to be established, the path indicator being established in a central processing unit, CPU,, wherein the at least one signal path is determined based on the detected connection statuses; wherein the term terminal refers to a structure to which a signal is input or from which a signal is output. a microphone terminal to which a sound signal derived from sound received by a microphone is input; a loudspeaker terminal from which a sound signal directed to a loudspeaker is output; a first input terminal to which a sound signal from an other device at a proximal-end is input, wherein the term proximal-end refers to a signal that does not pass through a network; a first output terminal from which a sound signal directed to the other device is output; a distal-end input terminal to which a distal-end sound signal is input via a network, wherein the term distal-end refers to a signal passing through the network; a distal-end output terminal from which a sound signal directed to the network is output; a detector configured to detect a connection status of a subject device to the network and a connection status of the other device to the network, the subject device being a sound emission-reception apparatus and the other device being a proximal-end sound emission-reception apparatus other than the subject device; a path establisher configured to establish at least one signal path from at least one of the microphone terminal, the first input terminal, or the distal-end input terminal, to at least one of the loudspeaker terminal, the first output terminal, or the distal-end output terminal, the path establisher being established in a digital signal processor, DSP,; and a path indicator configured to indicate to the path establisher a signal path that is to be established, the path indicator being established in a central processing unit, CPU,, wherein the at least one signal path is determined based on the detected connection statuses; wherein the term terminal refers to a structure to which a signal is input or from which a signal is output.