Before entering the Control Room from the galley you pass the Radio Room where encrypted messages were sent and received, and a radio operator was always on watch when the
ship was on or near the surface. When encrypted messages were received, an officer would operate the code machine to decrypt the message, often with the skipper himself watching closely as the message revealed its contents.
For information on all the radio equipment in the radio room see the radio catalogue.
For information on the electronic cipher machine, see the ECM Mark II page.
You will also see a small grey box with a phone handset next to it that has a dial on the bulkhead. This is a sound powered phone. After selecting the compartment you wish to speak to with the dial, you can turn the crank to ring their phone.