I fear the passengers are all dead. I read a very compelling possibility to what happened to them.
I couldn't quite get the cell phone thing. Cell phones that are off or dead go straight to voice mail, yet many were still ringing hours after the plane went missing.
Then it made sense to me. After 9/11 the U.S. government conducted tests to see what problems the terrorists encountered in an effort to understand how to thwart a further attack of this nature. One of the major problems were dealing with, and controlling, the passengers. The plane that crashed in Pa. did so because of the efforts of the passengers. What the U.S. gov. determined was that if you could easily kill or disable them this would be a great help. They found that if a pilot ascended to 40,000 to 45,000 ft. and depressurized the cabin, the passengers would become unconscious and die very quickly, while the pilot's cabin would have additional oxygen.
If you remember very early on the report about how the plane ascended very high, very fast, then descended and flew under radar. This seems not only plausible, but in my opinion, likely. My gut tells me that this plane is in Pakistan getting retooled for something very bad. I pray I'm wrong.