The T-52 G-Schreiber was developed around 1930 by Siemens & Halske. It was used by the Germans in WWII in conjunction with the Enigma and Lorenz. Intercepting messages that were in-depth enough to decipher was difficult for Allied codebreakers because it was used via land lines and only occasionally over radio. However, it was possible and Swedish and British codebreakers were able to decipher pieces of traffic ciphered by the machine Bletchly Park(UK) dubbed "STURGEON".
Siemens & Halske
Still Image Item Type Metadata
Siemens & Halske, “G-Schreiber "STURGEON",” Ciphers and Encryption, accessed October 22, 2021, https://crypto.omeka.net/items/show/18.