I got a call from this number and no message was left on my machine. The caller id said "Fullerton UHSD" but when I ran a trace on the number it didn't come back as Fullerton Union High School District, in fact it was blocked. Now why would a public high school district block their identity. Probably because this it is a spoofed number being used by some scammer.
Here is the real information:

Fullerton Union High School
School in Fullerton, California · fullertonhigh.org
Fullerton Union High School is a public high school located in the Orange County, California city of Fullerton, United States operated by the Fullerton Joint Union High School District. Wikipedia
Address: 201 E Chapman Ave, Fullerton, CA 92832
District: Fullerton Joint Union High School District
Founded: 1893
Phone: (714) 626-3800
School board: Fullerton Joint Union High School District
Highest grade: Twelfth grade
Lowest grade: Ninth grade

Fullerton Joint Union High School District
1051 W. Bastanchury Rd., Fullerton, CA 92831
Phone 714-870-2800 | Fax 714-870-2807