full duplex radio

good day…newbie here (please be nice lol)

i was told that there is a way for standard two way radios to operate in full duplex or like a mobile phone. the guy tells me that we have to short something on the circuitboard of the radio. i’d like to know what that is or if it isn’t done that way, any suggestions on how to make a normal VHF transceiver operate in full duplex?