It's too high pitched to be an STL-10. It has the same pitch as a T-128 but I don't think it's rotating and I doubt they would use that indoors. Maybe a T-121 or something similar.
My family will not answer the phone under any circumstances unless they recognize the number. Any other family that does this will be unaffected by reverse 911. That could prove fatal during a severe weather event.
I'm gonna major in meteorology, and I love looking at the readings for that day. Its amazing how we've had countless scenarios where it looked like/worse then the Super Outbreak but none have came close.