A female mecha pilot tries to keep in touch with her boyfriend on earth while she is in space using cell phone text messages. The farther away they get from each other, the harder it is for the text messages to get to each other.

Special Note:
This OVA is a 30-minute Japanese anime OVA conceived, directed, and animated by one man only (Makoto Shinkai) !!! More info can be found at Wikipedia here.