Haha, good point. I agree with everyone though nobody seems to mention his rapid movement speed and action though, he would nearly have to teleport. There was a lot of confusion in that story.

any confusion can be explained by us getting the story second-hand from a ditzy college kid.

I'm glad to see this thread, because I thought I had just missed something huge there. This plot hole ruined this segment for me, which I thought was the best segment of the film. It just left me confused, and not scared.
"The success of the horror genre has led to its downfall."
-Dario Argento

Yup, that fail was just too obvious. The sad part is, having her call the cops wouldn't have thrown off the rest of the story at all, since the cops would be going over Ms. Burch's house, and not the call center where the rest or the story
takes place anyways. I mean, why not just toss that call in there? Or have her tell her boss to call the police, because she's getting out of there.
Anyways, your observation was definitely the most obvious flaw in the whole movie, so I believe it was astute of you to point it out here. Good job.

True!!! She should have called the police when she knew something had happened to the client.

You missed the point. She called the home of the woman who was being stalked. The stalker answered from that woman's phone. All manner of alarms should sound right there. If you call a woman fearing for her life and the person whom she fears answers, you should probably call the police right away.

Yeah I know that was retarded.

Yeah I know that was retarded.

Yeah, I thought she should've called the police, as well. It was like, it's okay if her boss comes in and gets killed by some maniac. Not only that, but didn't she know that the psycho was in the building, because she called that woman's room and the killer answered?

Her first call should have been to the police. No excuses.

She didn't think he was in the building yet because she didn't realize he got past the security guard. She called her boss to tell her that she was leaving and still thought he wasn't in the building yet until he realized that he was calling from the phone inside that the security guard had picked up.
Sure, she could have called the police herself but for a while she didn't think he was in the building yet and relied on the security guard to call the police.
Also, let's face it. A big part of horror stories rely on the victims to not think clearly or do stupid things.