A periscope was vital for discreet surveillance and battle command. With the help of this device the commandant was supervising the battlefield and was giving instructions to the crew in accordance with the coordinate grid map. At the same time the periscope (and the place where the periscope was set up) was one of the weakest points of a pillbox. After knocking it out with a direct explosion, gasoline was poured into the opening and shells were thrown inside, which allowed the enemy to destroy the whole crew at once.
The voice pipes were the main means of the inside communication, as they connected the commandant’s compartment with the combat posts.The communication between the nearby buildings was carried out through a telephone and a short-wave radio station.