All Chinese diplomatic missions abroad have radio antennae on their roof for direct communications with Beijing. Their radio rooms have radio operators and cryptographers, as well as secretaries who handle classified and confidential documents. These "confidential personnel" work under boring and confining conditions, as they are seldom permitted to leave the embassy compound lest they be compromised by adversary intelligence agencies. Chinese embassies have special secure units made of special building materials for holding important meetings and for transmitting and receiving radio messages.
Another task of the diplomatic radio is receiving intelligence and requests for instructions from agents stationed abroad, and transmiting orders and instructions from the secret service headquarters. The diplomatic radio was very active in the 1950s and 1960s, though over the years its importance has declined.