Mobile phones

Okay, this was the 21st century (the wristwatch Amy and her friends found on the body was inscribed 2002), so why did nobody even try to use a mobile phone (cellphone)? I don't believe in this day and age the five students and Carrie wouldn't have had them. Yes, it's possible that there was no reception in the area, but surely somebody would have tried! It's the first thing most people in danger do these days!