Mid-war, the Wehrmacht was faced with materials shortages, financial strains, and bombed out production facilities. There was a need to simplify and cost reduce manufactured products for the war effort. These products included field telephones. In 1943, the Feldfernsprecher 33 (FF33) field telephone was redesigned to become the OB Fernsprecher 43 (a.k.a. the OB43). Production of the FF33 continued until wars end and later into the early 1960s.
Since there was no weather seals on its case, the OB43 was intended to be used indoors only, in offices off the battlefield. Metal hardware was eliminated where possible. The piano hinge on the lid was replaced by two short hinges. There was no attachments for a sling, no cover for the crank hole, no grilles over the bell holes (and no bell holes), and no patch cord sockets.
Inside the OB43, the handset plug was eliminated and the handset was permanently wired to the frame. The metal frame itself was eliminated. It was replaced with a rectangular phenolic resin board. The wire terminal knobs were plastic and there was no battery cup. Otherwise, the function of the OB43 was identical to the FF33.
The OB43 was produced only during the late war, so it is relatively rare today. Most of the surviving OB43 telephones were given to Scandinavian armies after the war. They were modified slightly, most notably, the red plates were removed from the tops of the lids.
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WW2 German Field Telephone Equipment 