Interestingly Wikipedia says the Morse version of it is Morse code "dah-di-di-dah-di, dah-dit" ( –··–· –· ) IMHO more common is to send "ESE" (. ... .) -

Interestingly Wikipedia says the Morse version of it is Morse code "dah-di-di-dah-di, dah-dit" ( –··–· –· ) IMHO more common is to send "ESE" (. ... .) - and the other station replies "EE" (. .) https://lcwo.net/ext/player?z=MjR%2BfjIwfn42MDB%2BfkVTRSBFRQ%3D%3D https://lcwo.net/ext/player?z=MjR%2BfjIwfn42MDB%2BfkVTRSBFRQ... "ESE" is a popular Amateur radio call-sign suffix among Morse enthusiasts for that reason.