HOMSECUR 520C-6 Telecamera da Esterno per Videocitofono Citofono Campanello 6 Famiglie
If you have HOMSECUR. Handsfree Dual-way Intercom and Indoor Monitoring. The outdoor unit has 6 call buttons for calling the separate room. Press the answer button, then you can talk to outside, press the answer button again to turn it off.