I personally think this is the best kdrama from first half of 2019 or at least in top 3.

If I was to compare out of the trilogy this would be my standing on it.
Voice 3> Voice> Voice 2

Story:
From start to finish, there was so much going on and nothing was slow. The antagonist was well written. Also Kouske! kouske, kouske. Boy did I love how he stayed true to his character! It took alot of things Voice 2 needed improvement and truly made it into a masterpiece. Also thank god there was no romance or else the whole show could have been ruined!

Acting/Cast: Amazing acting from Lee Jin Wook, Kang Center, and the antagonist. However, I think there could have been some improvements from the call center support cast such as Seo Eun Seo and Kim Woo Suk.

Music: it fitted well especially BLOO Open Your Eyes was such a good modern match! I wish they played it more in the show.

Ending: I liked the ending. It was great.

Hoping OCN create a season 4 plss ;) there is so many possibilities, it is a waste not to.