Good questions. I wondered that myself.
Small correction: she texted her bf at 4:47am, called the cab at 5:05am. Phone was shut off at 5:07am.
http://www.azcentral.com/community/...ching-missing-tempe-woman.html?nclick_check=1
IMO, unless her phone was on it's last legs as far as charge is concerned, and it either died or she felt the need to turn it off to reserve battery charge, she did not place that call for a cab. Or if she did, it was done under duress and there was no intent for her to ever go to that location. Just a red herring to throw LE off for a while.
MOO