The head of Dane County's 911 center has responded to reports of a call made by Brittany Zimmerman the day the UW Madison student was murdered. Joe Norwick says the 911 dispatch center did receive a call from Zimmerman's cell phone on April 2 — although there was no sound from the caller. The dispatcher answered two more calls, and although protocol is for the dispatcher to call back non-responsive callers, they were busy and never got around to it. Norwick disputes allegations that a dispatcher did try to call Zimmerman back, but had the wrong number. Because Zimmerman used her cell phone, it was hard to track. Had she had a land line, the address would have popped up.