A voice-call system comprising: a gateway configured to collect monitoring information from a monitoring terminal installed in a residence, the monitoring terminal is configured to detect the presence or absence of an abnormality, wherein when detecting the occurrence of an abnormality, the monitoring terminal is configured to transmit the monitoring information for reporting the occurrence of the abnormality to the gateway; at least one voice-call terminal including an operation section operated to start a notification by voice, a microphone, and a speaker; a monitoring device used by a company that provides security service; and a server device configured to relay communication between the gateway and the monitoring device, wherein, when receiving the monitoring information from the monitoring terminal, the gateway is configured to transmit the monitoring information to the server device, and the gateway is configured to transmit to the voice-call terminal, a control signal for putting the voice-call terminal into a transmission state, wherein the server device is configured to transfer, to the monitoring device, data based on the monitoring information transmitted from the gateway, and transfer, to the gateway, data including a control command transmitted from the monitoring device, and wherein, when the voice-call terminal is put into a transmission state, the voice-call terminal is configured to transmit, to the monitoring device via the gateway and the server device, a first speech signal converted into an electric signal by the microphone, and output, by voice from the speaker, a second speech signal transmitted from the monitoring device via the server device and the gateway. a gateway configured to collect monitoring information from a monitoring terminal installed in a residence, the monitoring terminal is configured to detect the presence or absence of an abnormality, wherein when detecting the occurrence of an abnormality, the monitoring terminal is configured to transmit the monitoring information for reporting the occurrence of the abnormality to the gateway; at least one voice-call terminal including an operation section operated to start a notification by voice, a microphone, and a speaker; a monitoring device used by a company that provides security service; and a server device configured to relay communication between the gateway and the monitoring device, wherein, when receiving the monitoring information from the monitoring terminal, the gateway is configured to transmit the monitoring information to the server device, and the gateway is configured to transmit to the voice-call terminal, a control signal for putting the voice-call terminal into a transmission state, wherein the server device is configured to transfer, to the monitoring device, data based on the monitoring information transmitted from the gateway, and transfer, to the gateway, data including a control command transmitted from the monitoring device, and wherein, when the voice-call terminal is put into a transmission state, the voice-call terminal is configured to transmit, to the monitoring device via the gateway and the server device, a first speech signal converted into an electric signal by the microphone, and output, by voice from the speaker, a second speech signal transmitted from the monitoring device via the server device and the gateway.