On the Line (2021)

When BYH 1st goes to the voice phishing office and got his red numbered jacket it felt like a scene from Squid Game
The basic idea was the same, guy goes undercover in a place that lied to people and used their weaknesses for money and entertainment

Both are films about voice phishing. Protagonists cannot find help from the authorities, so they take matters into their own hands.

Both movies show victim's life, and behind of that, there's professional scamming group which has 100+ people. Investigation.

Both of the dramas have Voice phishing and Revenge. Both are very sad to watch. Although taxi driver deals with different people, on the line focuses on one

Both deal with voice calls and helping victims that are affected.
Both shows have the same title 'Voice'.