Walkie talkie can work through the wall depending on whether you're using a UHF or VHF walkie. UHF has a wider signal range than VHF and thus tends to penetrate any objects that is in the path of transmission better. Thus, it can be said that a UHF walkie can penetrate walls but that will depend on the strength of the brand/model of the walkie talkie and what range does it claim to work.