Morse code sounded in the Commons as an MP wished happy birthday to a British intelligence agency.
Conservative MP Alex Chalk held his phone up to a microphone in the chamber to allow the long and short beeps spelling out the message to be heard.
It was aimed at GCHQ, which is based in his Cheltenham constituency, as it marks its 100th anniversary.
Concluding his speech, Mr Chalk said: "GCHQ's centenary just so happens to coincide with the 175th anniversary of the first use of Morse code to send a message between cities.
"So it's therefore perhaps fitting I should conclude with a message to GCHQ in the form of Morse code.
"This will last for the next 13 seconds, Mr Speaker."
After the beeps finished, he added: "Happy birthday to GCHQ."
Speaker John Bercow added: "I think the whole House is grateful to (Mr Chalk) for bringing this debate and for the way in which he has conducted it."
Foreign Office minister Sir Alan Duncan also said Mr Chalk had concluded his speech in a "unique and historical way", adding: "He has the added advantage of being one of the few members of this House who can actually reach the microphone above him."