In the 1960s, the German company Siemens introduced the Fg 30/5032 c I analog charge indicator. The cover is made of light-gray plastic. It has a metal base bearing the model, date of manufacture, company logo e.t.c. Its mechanism consists of a timer. At the bottom of the device, there is a slot for a key; turning it would reset the counter, allowing a new call to be made. The wiring diagram, printed on paper, was located inside the device. It remained in production until the mid-1970s. Its dimensions were 19 cm x 9 cm x 7 cm. In Greece, the sole customer for these devices was the Hellenic Telecommunications Organization (OTE S.A.), which managed the public telephone network.