I Picked a Mobile From Another World

I Picked a Mobile From Another World is a Manga/Manhwa/Manhua in (English/Raw) language, Action series, english chapters have been translated and you can read them here.
The Summary is

In the midst of the devastation, only the soldiers’ bones remained.
It’s only a matter of time before the entire world is annihilated. To avoid this, Kyung-Hoon began searching for clues in another universe with the help of a ten-year-old phone he discovered in an abandoned building.