The Socotel S63 was the French standard telephone from the 1960s and contemporary to our Dutch T65. It was designed by the Centre national d’études des télécommunications as a replacement for the PTT 24 and the U43.
Besides the desk model, a wall version was also produced. The S63 came in a whole range of colors. The grey version was the most common by far, but you can find the colors Ivory, blue, brown, orange and red as well.
My S63 is a special transparant version, made in 1978.
Until 1974, depending on the distance between the telephone and the exchange, a fitting resistor was installed in the telephone. From 1975 onwards the S63 was produced wit a thermistor, which regulated its resistance automatically.