Hackers publish indexes containing phone numbers, names, and carriers. They use these to socially engineer mobile carriers into transferring a victim's number to a new SIM card, bypassing 2FA.
Seo-yeon’s mother (Eun-ae) fights Young-sook in 1999, and they both fall over a railing. In 2019, the older Young-sook disappears, and Seo-yeon is reunited with her mother. The "Cruel" Twist (Mid-Credits): index of the call 2020