Pulse (2006)

In this English language adaptation of the Japanese thriller "Kairo", an apparently innocent website turns out to be run by a sinister and deadly force. At first the site appears to be merely a scary hoax with an irresistible marketing plot, but when a group of college friends hack into a wireless frequency that transmits between nearly every electronic device, they inadvertently open a "doorway" allowing ghosts to pass through. Send an e-mail, answer your cell phone, check your blackberry, and they will find you. One by one, students succumb to the ghostly creatures now haunting the campus.

Official website: http://www.pulsethemovie.net/