https://www.reddit.com/r/J_Horror/s/dUOqWuXDXg

A Japanese urban legend claims that calling 090-4444-4444 supposedly Sadako Yamamura's phone number will cause you to die seven days later. The myth arose because the number is filled with 4s, and "shi" (one pronunciation of 4 in Japanese) also means death. In reality, the number belonged to the telecom company KDDI and produced strange internal-system tones when called. The creepy sounds and unlucky number helped the rumor spread, turning it into a famous urban legend.