After interception, the encrypted messages were taken down on paper and sent to...
… Bletchley Park by motorcycle or teleprinter. The various messages were then sent to the relevant sections − all German naval messages, for example, went to the Naval Section, all German Air Force messages went to the Air Section.The sections noted down all of the details from the message for inclusion in a central index. They also analysed what the enemy wireless operators said to each other. This process, part of what is known as ‘Traffic Analysis’, often produced very important intelligence.
All Army and Air Force Enigma messages went to Hut 6 where the details of each message were taken down and indexed. A separate ‘Traffic Analysis’ section known as SIXTA worked as part of Hut 6 to analyse the communications around the messages and throw up clues for the codebreakers.
Naval Enigma messages went to both Hut 8, where they were broken, and to Hut 4, which carried out a similar ‘Traffic Analysis’ process to SIXTA for the Hut 8 naval codebreakers.
Later in the war all enciphered Tunny teleprinter messages went to the Newmanry and the Testery where they were deciphered with the assistance of the ‘Colossus’ machine.