Talk:Skype/@comment-26130759-20150221023842

I liked it and here's my interpretation for those who may be asking about the letter and the lack of response at the end:

Earlier on in the story, Annie mentioned her flatmate Erin. Erin disappeared during the previous fire-alarm and left a letter on her desk saying that she went home (probably her parent's home).

The killer then leaves an envelope on Annie's desk during this fire-alarm.

Moving on, possible explanations why someone does not respond on the phone are countless, but in this context maybe he was at a loss for words at the horror of what happened on screen, or that something happened to him too (maybe the killer is supernatural?)

I agree with some that it is strange the person on the line did not notice him yelling loudly.