Safety first: This high-tech gadget works like a traditional bell, but has a spy camera and a two-way speaker system An increasing number of households are replacing their traditional doorbell with a new 'smart' version due to security fears. This high-tech gadget works like a traditional bell, but has a spy camera and a two-way speaker system that allows you via your mobile phone to see and talk to anyone standing on your doorstep. It could prove particularly useful when lockdown ends and fewer people are at home to answer their front door. Using Wi-Fi, the smart doorbell sends a text to your mobile stating someone is on your doorstep.