La Habra bomb threat

This morning students at Sonora High in La Habra had a break from school after authorities received a bomb threat at 7:30am. A "suspicious duffel bag" was found and removed; nobody was hurt. No word on what was found in the duffel bag, or if they blew it up, like they sometimes do.

Students were sent back into class around 11am. The school is, by the way, in the middle of finals week. Hmmmm.

The bomb threat came from a TTY phone, which are the kind used by people who are hearing-impaired. Seems like that might be kind of a giveaway. Or is there some fancy cloak-and-dagger mechanism that makes those calls harder to track? Was this actually a stroke of teenage, finals-avoiding genius?