Kocchi Muite! Miiko

The continuation of Miiko Desu!
This time, Miiko is in the fifth grade, and the stories have become more exciting! (Doko Demo Doa Manga Scanlations)

This series received the 1996 Shogakukan Manga Award for children's manga.

Ano Hi Kara no Denwa:
Haruna’s father buys a new cell phone and gives his old one to her baby sister to play with. It’s old-fashioned and heavy, but Haruna discovers that this phone has a secret power… -cloudcake16-

(Source: MangaUpdates)