Melody of Anokata’s number

[ALAKTORN 170]

http://www.detectiveconanworld.com/wiki/Nanatsu_no_Ko

“Conan noticed that the first few notes sounded very close to the area code for Tottori prefecture. He guessed that it was a song starting with notes "B A G A". He discovered the song Nanatsu no Ko matched the sound of the key presses after asking Kyosuke Haga‎ what songs start with "H A G A".”

http://www.detectiveconanworld.com/wiki/Kyosuke_Haga#Kyosuke_Haga

“When Kyosuke was being taken away by the police, Conan asked him if he knew any songs that began with "B A G A" (or "H A G A").”

From what I gather H is used in some places of the world while B is used in others, hence the mixage. But what I wanted to ask is: why are we using those letters, instead of what Conan actually says most of the time, that it’s a “Si La Sol La” melody?

https://www.youtube.com/watch?v=-JMw61NMs4w (near end)

Conan there says something like “When I asked you about the melody, you replied “Is it something about me?””. Then says something about it being H A G A therefore Haga in German or whatever, don’t know. Then says “Then that melody really is Si La Sol La”. Then he asks Haga if he knows any songs that start with “Si La Sol La”.

I know nothing about music but I found this whole thing pretty confusing to read on the wiki. Maybe it should all just be replaced with Si La Sol La?

[Chekhov MacGuffin 1089]

ABCDEFG notation is standard pretty much everywhere English speaking, which is what our wiki is aimed at. Only the Germans use H as far as I know, and they have their own wiki and aren't our problem. ABCDEFG is a far, far more common notation than the solfège (DoReMi).

[ALAKTORN 170]

Hmm OK. In Italy we use Do Re Mi.