＜Conan＞In which episode did Conan learn the area code of the location of the black organization BOSS through the sound of cell phone buttons?

Conan heard Vermonth press the number at the end of episode 345 and only remembered the first 4 tones

In episode 350, Conan thought that he could find the phone through its email address. Master, so he began to recall the key tone he heard that time

In Episodes 371-375, Conan learned that the area code of Tottori Prefecture is the first four tones when pressed on the mobile phone

Then in episodes 385-387, he found out that the song "Seven Children" happened to start with these four tones

In episode 394, Conan figured it out, because the organization didn't want the BOSS's email address to be revealed. That's why organization members don't save BOSS's email address in their mobile phone address book. Instead, they directly press the key every time. In order to make it easier to remember, BOSS's email address is set to a key tone that can be connected into a song. That's it. "Seven Children". So Conan roughly inferred the address through the tone of the song. Of course, it's a series of numbers.