Norm 51

When world war 2 ended PTT found itself with a severely damaged telephone network and a myriad of systems, exchanges and telephone models on the one side and an ever increasing demand from new subscribers and network capacity. Because of this situation a number if specifications were implemented one after the other, to which network and equipment had to conform. These so called Normen prescribed electrical, acoustic but physical properties too, to improve the quality of the connections, logistics and efficiency. After the Norm A in 1946, Norm B in 1948 in Norm 51 was implemented in 1951. The specifications laid down in Norm 51 would be in effect untille well into the 1980s.

Here a non exhaustive list of Norm 51 telephones:

  • BASA Norm 51
  • Heemaf Norm 51
  • Ericsson type 1951
  • NSEM type 1954
  • Heemaf type 1955
  • T65
  • Ericsson Diavox
  • NSEM Unifoon

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