The U43 was designed by Ericsson France, Société des Téléphones Ericsson. U stands for Universel (universal) and 43 for the year of introduction, 1943.
The housing is based ont the Ericsson 1931. The new model was to be produced for LB, CB and automatic exchanges. It was also required to be cheaper to produce than its predecessor, the PTT 24. As word war 2 was in full swing when this phone was developed, the use of strategic materials such as steel was avoided as much as possible and bakelite was chosen as the material for the shell.
This telephone was the French standart apparatus well into the 1960’s, when the Socotel 63 was introduced. The U43 was used by the French PTT as well as by the French railways, the SNCF.