This is my thinking. The odds that someone would not have sent out a text or made a call seem slim. Even if the pilots kept the passengers calm by claiming they were simply heading back because of weather or what not, someone would likely have been suspicious. And when they exit the plane, how do they get 200+ people to all hand over their phones at the same time without one of them realizing something isn't right and using it quickly. I just can't see this happening.