Hagenuk = Hanseatic apparatus construction company Neufeld and Kunke
Hanseatische Apparatebaugesellschaft Neufeld und Kunke
Handset capsule and connection cable is not original.
The rest, however, is very nicely stamped and also in a very nice and good condition, if the price fits - buy.
Original receiver capsule and connection cable are available for purchase and are easy to replace.