I Picked a Mobile From Another World is a Manga/Manhwa/Manhua in english language, Action series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.cc fastest updating comic site. 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.