Wireless Room
The Wireless Room is located on the port side of the forward Boat Deck. It is only accessible when you have spoken with Third Officer Morrow long enough to gain permission to enter.
Importance
After Carlson enters, have a look at the desk area where the telegrams are resting. In the drawers are stacks of telegrams, which must be searched until Carlson finds one with a series of numbers and letters. Using the cryptograph in Carlson's cabin, C-73, will reveal the whereabouts of the Rubaiyat:
“…Rubaiyat hidden in boiler room 3. coal chute 4. SB will deliver painting after pickup. Will confirm…”
Later on in the game, Carlson will enter the Purser's Office and hear him mumbling the name 'Thayer'. He will say that an urgent telegram must be sent and Carlson must offer to send it in order to proceed further in the game. Instructions on how to switch the Wireless on are found on the table. Note that you do not actually have to send the entire message to proceed with the game - merely turning on the machine, getting the telegram out and tapping some random gibberish letters will be enough for the game to accept that you have sent it.
You can also set the machine to receive rather than transmit, enabling you to listen to some messages from other ships warning about icebergs and pack and field ice within the immediate vicinity of Titanic.
Trivia
It is highly unusual - and historically inaccurate - that the Wireless Room would be vacant, as the ship's real life wireless operators Jack Phillips and Harold Bride were desperately attempting to clear a huge backlog of telegrams that Sunday night, right up until the moment the ship struck the iceberg.
Furthermore, the coded messages being sent by Zeitel would almost assuredly increase the suspicions of the wireless operators.